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Gymnosperm Stem: Epidermis and Cortex in Two Year Pinus

cross section: Pinus stem magnification: 400x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. cross section: Pinus stem magnification: 400x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous.

Gymnosperm Stem: Pith in Two Year Pinus

cross section: Pinus stem magnification: 400x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 400x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Gymnosperm Stem: Phloem in Three Year Pinus

cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Herbaceous dicot vine: Xylem vessels in Cucurbita

long section: Cucurbita stem magnification: 400x Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells. long section: Cucurbita stem magnification: 400x Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells.

Gymnosperm Stem: Resin Duct in Three Year Pinus

cross section: Pinus stem magnification: 100x Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. cross section: Pinus stem magnification: 100x Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem.

Angiosperm Morphology: Bulliform Cells in Zea Leaf

cross section:Zea leaf common name: corn magnification: 400x The iso-bilateral leaf of Zea is typical of most monocots. Both upper and lower epidermis are uniseriate and well cutinized. Within the upper, or adaxial, epidermis, large white bulliform cells shrink, allowing the leaf to roll during drought. Stomata are present on both surfaces with guard cells perched above small round substomatal chambers. As with most monocots the mesophyll is unspecialized, being composed of compactly arranged somewhat round chlorenchyma cells. Numerous small and occasionally large vascular bundles are arranged in parallel series along the length of the leaf. The vascular bundles are collateral and closed with xylem of vessels and tracheids towards the adaxial surface and phloem of sieve tubes and companion cells towards the abaxial surface. Cambium is not present. Within each bundle a xylem of two oval metaxylem and a single large protoxylem cavity can be seen. Each vascular bundle is wraped by a bundle sheath of thin walled parenchyma cells. Larger bundles are supported towards both surfaces by masses of sclerenchyma that interrupt the mesophyll to form a patchy hypodermis. cross section:Zea leaf common name: corn magnification: 400x The iso-bilateral leaf of Zea is typical of most monocots. Both upper and lower epidermis are uniseriate and well cutinized. Within the upper, or adaxial, epidermis, large white bulliform cells shrink, allowing the leaf to roll during drought. Stomata are present on both surfaces with guard cells perched above small round substomatal chambers. As with most monocots the mesophyll is unspecialized, being composed of compactly arranged somewhat round chlorenchyma cells. Numerous small and occasionally large vascular bundles are arranged in parallel series along the length of the leaf. The vascular bundles are collateral and closed with xylem of vessels and tracheids towards the adaxial surface and phloem of sieve tubes and companion cells towards the abaxial surface. Cambium is not present. Within each bundle a xylem of two oval metaxylem and a single large protoxylem cavity can be seen. Each vascular bundle is wraped by a bundle sheath of thin walled parenchyma cells. Larger bundles are supported towards both surfaces by masses of sclerenchyma that interrupt the mesophyll to form a patchy hypodermis.

Herbaceous Dicot Stem: Parenchymatous Pith in Older Helianthus

cross section: Older stem: Helianthus common name: Sunflower magnification: 100x All vascular tissues in Helianthus are the product of primary growth. There are no signs of secondary growth (growth rings or lateral meristems) as might be seen in woody stems. The uniseriate and cutinized epidermis contains large multicellular trichomes and occasional stomata. The cortex consists of an outermost hypodermis of heavy walled collenchyma, a deeper layer of parenchyma and a deepest band of endodermis (starch sheath). Within the stele the vascular bundles are arranged in a ring and separated from each other by wide medullary rays of parenchyma cells. The collaterally arranged vascular bundles are almost entirely primary phloem and xylem. Each bundle consists of a large outer supportive cap of sclerenchyma fibers (phloem fiber cap), a deeper layer of primary phloem with well-defined sieve tubes and companion cells, and a deepest layer of primary xylem. In between the xylem and phloem, a narrow band of cambium may be seen. In some preparations, the highly lignified cells walls of xylem and mature sclerenchyma are stained red orange. These cells are dead at maturity and can also be distinguished by a heavy cell wall and absence of cytoplasm. The center of the stem is occupied by a pith of parenchyma cells that contain numerous starch storing amyloplasts. cross section: Older stem: Helianthus common name: Sunflower magnification: 100x All vascular tissues in Helianthus are the product of primary growth. There are no signs of secondary growth (growth rings or lateral meristems) as might be seen in woody stems. The uniseriate and cutinized epidermis contains large multicellular trichomes and occasional stomata. The cortex consists of an outermost hypodermis of heavy walled collenchyma, a deeper layer of parenchyma and a deepest band of endodermis (starch sheath). Within the stele the vascular bundles are arranged in a ring and separated from each other by wide medullary rays of parenchyma cells. The collaterally arranged vascular bundles are almost entirely primary phloem and xylem. Each bundle consists of a large outer supportive cap of sclerenchyma fibers (phloem fiber cap), a deeper layer of primary phloem with well-defined sieve tubes and companion cells, and a deepest layer of primary xylem. In between the xylem and phloem, a narrow band of cambium may be seen. In some preparations, the highly lignified cells walls of xylem and mature sclerenchyma are stained red orange. These cells are dead at maturity and can also be distinguished by a heavy cell wall and absence of cytoplasm. The center of the stem is occupied by a pith of parenchyma cells that contain numerous starch storing amyloplasts.

Herbaceous dicot vine: Cucurbita

long section: Cucurbita stem magnification: 100x Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells. long section: Cucurbita stem magnification: 100x Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells.

Gymnosperm Stem: Medullary Rays Three Year Pinus

cross section: Pinus stem magnification: 100x Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. cross section: Pinus stem magnification: 100x Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem.

Gymnosperm Stem: Cork and Cortex in Three Year Pinus

cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Gymnosperm Stem: Annual Rings in Three Year Pinus

cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Gymnosperm Stem: Medullary Rays in Three Year Pinus

cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Herbaceous dicot vine: Cucurbita

long section: Cucurbita stem magnification: 40x The epidermis is usually single layered with an outer cuticle and multicellular trichomes. The cortex consists of a conspicuous hypodermis of parenchyma cells with collections of collenchyma cells at the stem ridges. The deepest layer of the cortex is marked by a starch sheath (large barrel-shaped cells contain starch granules). Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells. long section: Cucurbita stem magnification: 40x The epidermis is usually single layered with an outer cuticle and multicellular trichomes. The cortex consists of a conspicuous hypodermis of parenchyma cells with collections of collenchyma cells at the stem ridges. The deepest layer of the cortex is marked by a starch sheath (large barrel-shaped cells contain starch granules). Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells.

Herbaceous dicot vine: Xylem vessels in Cucurbita

long section: Cucurbita stem magnification: 400x Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells. long section: Cucurbita stem magnification: 400x Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells.

Gymnosperm Stem: Two Year Pinus

cross section: Pinus stem magnification: 40x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 40x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Gymnosperm Stem: Cambium in Three Year Pinus

cross section: Pinus stem magnification: 400x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 400x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Gymnosperm Stem: Cortical Resin Duct in Three Year Pinus

cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Gymnosperm Stem: Three Year Pinus

cross section: Pinus stem magnification: 40x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 40x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Gymnosperm Stem: Three Year Pinus

cross section: Pinus stem magnification: 100x Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. cross section: Pinus stem magnification: 100x Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem.

Herbaceous dicot vine: Cucurbita

long section: Cucurbita stem magnification: 100x Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells. long section: Cucurbita stem magnification: 100x Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells.

Herbaceous dicot vine: Cucurbita

long section: Cucurbita stem magnification: 40x The epidermis is usually single layered with an outer cuticle and multicellular trichomes. The cortex consists of a conspicuous hypodermis of parenchyma cells with collections of collenchyma cells at the stem ridges. The deepest layer of the cortex is marked by a starch sheath (large barrel-shaped cells contain starch granules). Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells. long section: Cucurbita stem magnification: 40x The epidermis is usually single layered with an outer cuticle and multicellular trichomes. The cortex consists of a conspicuous hypodermis of parenchyma cells with collections of collenchyma cells at the stem ridges. The deepest layer of the cortex is marked by a starch sheath (large barrel-shaped cells contain starch granules). Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells.

Angiosperm Morphology: The Closed and Collateral Vascular Bundle in Zea

cross section:Zea leaf common name: corn magnification: 400x The iso-bilateral leaf of Zea is typical of most monocots. Both upper and lower epidermis are uniseriate and well cutinized. Within the upper, or adaxial, epidermis, large white bulliform cells shrink, allowing the leaf to roll during drought. Stomata are present on both surfaces with guard cells perched above small round substomatal chambers. As with most monocots the mesophyll is unspecialized, being composed of compactly arranged somewhat round chlorenchyma cells. Numerous small and occasionally large vascular bundles are arranged in parallel series along the length of the leaf. The vascular bundles are collateral and closed with xylem of vessels and tracheids towards the adaxial surface and phloem of sieve tubes and companion cells towards the abaxial surface. Cambium is not present. Within each bundle a xylem of two oval metaxylem and a single large protoxylem cavity can be seen. Each vascular bundle is wraped by a bundle sheath of thin walled parenchyma cells. Larger bundles are supported towards both surfaces by masses of sclerenchyma that interrupt the mesophyll to form a patchy hypodermis. cross section:Zea leaf common name: corn magnification: 400x The iso-bilateral leaf of Zea is typical of most monocots. Both upper and lower epidermis are uniseriate and well cutinized. Within the upper, or adaxial, epidermis, large white bulliform cells shrink, allowing the leaf to roll during drought. Stomata are present on both surfaces with guard cells perched above small round substomatal chambers. As with most monocots the mesophyll is unspecialized, being composed of compactly arranged somewhat round chlorenchyma cells. Numerous small and occasionally large vascular bundles are arranged in parallel series along the length of the leaf. The vascular bundles are collateral and closed with xylem of vessels and tracheids towards the adaxial surface and phloem of sieve tubes and companion cells towards the abaxial surface. Cambium is not present. Within each bundle a xylem of two oval metaxylem and a single large protoxylem cavity can be seen. Each vascular bundle is wraped by a bundle sheath of thin walled parenchyma cells. Larger bundles are supported towards both surfaces by masses of sclerenchyma that interrupt the mesophyll to form a patchy hypodermis.

Gymnosperm Stem: Two Year Pinus

cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Gymnosperm Stem: Cork in Three Year Pinus

cross section: Pinus stem magnification: 400x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. cross section: Pinus stem magnification: 400x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins.

Herbaceous dicot vine: Cucurbita

long section: Cucurbita stem magnification: 100x The epidermis is usually single layered with an outer cuticle and multicellular trichomes. The cortex consists of a conspicuous hypodermis of parenchyma cells with collections of collenchyma cells at the stem ridges. The deepest layer of the cortex is marked by a starch sheath (large barrel-shaped cells contain starch granules). long section: Cucurbita stem magnification: 100x The epidermis is usually single layered with an outer cuticle and multicellular trichomes. The cortex consists of a conspicuous hypodermis of parenchyma cells with collections of collenchyma cells at the stem ridges. The deepest layer of the cortex is marked by a starch sheath (large barrel-shaped cells contain starch granules).

Gymnosperm Stem: Pith in Three Year Pinus

cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 100x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Herbaceous dicot vine: Cucurbita

long section: Cucurbita stem magnification: 40x Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells. long section: Cucurbita stem magnification: 40x Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells.

Herbaceous dicot vine: Vascular bundles in Cucurbita

long section: Cucurbita stem magnification: 400x Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells. long section: Cucurbita stem magnification: 400x Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells.

Angiosperm Morphology: The Monocotyledonous Leaf of Zea

cross section:Zea leaf common name: corn magnification: 100x The iso-bilateral leaf of Zea is typical of most monocots. Both upper and lower epidermis are uniseriate and well cutinized. Within the upper, or adaxial, epidermis, large white bulliform cells shrink, allowing the leaf to roll during drought. Stomata are present on both surfaces with guard cells perched above small round substomatal chambers. As with most monocots the mesophyll is unspecialized, being composed of compactly arranged somewhat round chlorenchyma cells. Numerous small and occasionally large vascular bundles are arranged in parallel series along the length of the leaf. The vascular bundles are collateral and closed with xylem of vessels and tracheids towards the adaxial surface and phloem of sieve tubes and companion cells towards the abaxial surface. Cambium is not present. Within each bundle a xylem of two oval metaxylem and a single large protoxylem cavity can be seen. Each vascular bundle is wraped by a bundle sheath of thin walled parenchyma cells. Larger bundles are supported towards both surfaces by masses of sclerenchyma that interrupt the mesophyll to form a patchy hypodermis. cross section:Zea leaf common name: corn magnification: 100x The iso-bilateral leaf of Zea is typical of most monocots. Both upper and lower epidermis are uniseriate and well cutinized. Within the upper, or adaxial, epidermis, large white bulliform cells shrink, allowing the leaf to roll during drought. Stomata are present on both surfaces with guard cells perched above small round substomatal chambers. As with most monocots the mesophyll is unspecialized, being composed of compactly arranged somewhat round chlorenchyma cells. Numerous small and occasionally large vascular bundles are arranged in parallel series along the length of the leaf. The vascular bundles are collateral and closed with xylem of vessels and tracheids towards the adaxial surface and phloem of sieve tubes and companion cells towards the abaxial surface. Cambium is not present. Within each bundle a xylem of two oval metaxylem and a single large protoxylem cavity can be seen. Each vascular bundle is wraped by a bundle sheath of thin walled parenchyma cells. Larger bundles are supported towards both surfaces by masses of sclerenchyma that interrupt the mesophyll to form a patchy hypodermis.

Stem submerged dicot: Nymphaea

cross section: Nymphaea stem magnification: 100x The bulk of the stem consists of open airy aerenchyma with numerous large air chambers that aide in respiration and buoyancy The vascular bundles are surrounded by a starch containing endodermis in which the red staining casparian strip may occasionally be seen. A pericycle can be seen beneath the endodermis. Like my hydrophytes, xylem tissues are reduced while phloem tissue are well developed and, in lager bundles may form in two distinct patches. cross section: Nymphaea stem magnification: 100x The bulk of the stem consists of open airy aerenchyma with numerous large air chambers that aide in respiration and buoyancy The vascular bundles are surrounded by a starch containing endodermis in which the red staining casparian strip may occasionally be seen. A pericycle can be seen beneath the endodermis. Like my hydrophytes, xylem tissues are reduced while phloem tissue are well developed and, in lager bundles may form in two distinct patches.

Gymnosperm Stem: Three Year Pinus

cross section: Pinus stem magnification: 40x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 40x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Gymnosperm Stem: Cambium in Two Year Pinus

cross section: Pinus stem magnification: 400x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts. cross section: Pinus stem magnification: 400x During the first year of growth the cutinized epidermis is replaced by protective growth of cork rich periderm. The outer periderm consists of layers of cork cells, the phellem, which produces waterproofing suberin. Cork cells are dead at maturity. Deep to the phellem is a living layer of cork cambium or phellogen and beneath that, layers of cork parenchyma or phelloderm. Many cells in the periderm contain dark staining tannins. The cortex is divided into a thin outer hypodermis of lignified sclerenchyma cells and thicker inner cortex of thin walled parenchyma cells containing chloroplasts. Large resin ducts are surrounded by secretory parenchyma that produces resins and turpentines. Some cells enlarge into dark staining tyloses. Both endoderm and pericycle are inconspicuous. The vascular cylinder or stele in young stems consists of a ring of vascular bundles interspaced with medullary rays of parenchyma cells. Seasonal activity of the cambium replaces the isolated vascular bundles with well-defined annual rings of secondary phloem and xylem. Xylem is endarch with protoxylem found towards center of the stem and younger metaxylem towards the periphery of the stem. Protoxylem consists of annular and spiral tracheids with only tracheids found in metaxylem. True xylem vessels are lacking. Because of the greater production of xylem, the vascular cylinder is dominated by radially arranged rays of secondary xylem interspaced with medullary rays of parenchyma cells. Conspicuous resin ducts are present throughout the xylem. Phloem is endarch but annual growth the of stem makes it difficult to distinguish between older protophloem to the periphery and younger metapholem towards center of the stem. Phloem lacks companion cells, consisting entirely of sieve tubes and phloem parenchyma. Medullary rays in the secondary phloem include protein rich albuminous cells. A well-defined pith of parenchyma cells is interrupted by a few large resin ducts.

Herbaceous dicot vine: Cucurbita

long section: Cucurbita stem magnification: 100x The epidermis is usually single layered with an outer cuticle and multicellular trichomes. The cortex consists of a conspicuous hypodermis of parenchyma cells with collections of collenchyma cells at the stem ridges. The deepest layer of the cortex is marked by a starch sheath (large barrel-shaped cells contain starch granules). Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells. long section: Cucurbita stem magnification: 100x The epidermis is usually single layered with an outer cuticle and multicellular trichomes. The cortex consists of a conspicuous hypodermis of parenchyma cells with collections of collenchyma cells at the stem ridges. The deepest layer of the cortex is marked by a starch sheath (large barrel-shaped cells contain starch granules). Bicollateral vascular bundles have two zones of phloem and two zones of cambium on either side of the central xylem with outer facing tissues more heavily developed. The sequence of tissues in the bicollateral vascular bundle is outer phloem, outer cambium, xylem, inner cambium and inner phloem with outer more heavily developed. Walls of xylem vessels have lignin free pits and lignin thickenings that form rings, spirals, networks and solid blocks. Phloem consists of large clear sieve tubes with pitted cell walls and sieve plates and small narrow green stained companion cells. Many sieve plates have deposits of a mucoid p-protein that forms as part of the trauma response in injured phloem. Between the xylem and phloem are a few regularly arranged layers of elongated cambium cells.

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