I know not that AESTHETIC it is just an overview....I hope it helps
I use this PowerPoint in my biology class at Beverly Hills High School.Topics:SeedsGymnospermsCycadsGinkgoConifersConifer life cycle
Explore the similarities and differences between angiosperms and gymnosperms. Get examples of each type of seed-bearing plant.
Gymnosperm life cyle
transverse or cross section: Pinus stem magnification: 400x iron-alum hematoxylin and safranin stain Berkshire Community College Bioscience Image Library Well defined annual rings of large diameter spring wood and smaller diameter autumn wood are composed entirely of narrow, relatively thin walled tracheids. The lumen of many tracheids is crossed by branched trabeculae. Tracheid side walls contain large circular bordered pits that function to move water from tracheid to tracheid while preventing air flow from embolized tracheids. Gymnosperms like Pinus rely entirely on tracheids for water flow and mechanical support. True xylem vessels and wood parenchyma are lacking. While fibers are generally absent older stems may contain some fiber tracheids. Xylem rays are uniseriate and composed of clear, thin walled parenchyma cells. Technical Questions:[email protected]
radial section: Pinus stem magnification: 400x iron-alum hematoxylin and safranin stain Berkshire Community College Bioscience Image Library Gymnosperms like Pinus rely entirely on tracheids for water flow and mechanical support. True xylem vessels and wood parenchyma are lacking. While fibers are generally absent older stems may contain some fiber tracheids. The uniform wood of Gymnosperms like Pinus consists almost entirely of longitudinally oriented bands of narrow, pale staining tracheids. Emerging at right angles are narrow xylem rays, one cell thick and a few cells high, and composed of clear, thin walled parenchyma cells. The lumen of many tracheids is crossed by branched trabeculae. Tracheid side walls contain large circular bordered pits that function to move water from tracheid to tracheid while preventing air flow from embolized tracheids. The membrane of each bordered pit is marked by a pale, thin, porous outer margo and thicker, darker, inner torus. Also emerging at right angles are occasional large resin ducts, lined with living secretory parenchyma that produce resins and many toxic terpenes including turpentines. Technical Questions:[email protected]
cross section: Pinus needle magnification: 400x Triarch quadruple stain Berkshire Community College Bioscience Image Library Deep to the hypodermis lies an undifferentiated photosynthetic mesophyll. Cells are distinctively lobed with infolded cell walls. They are filled with chloroplasts and starch grains that may be difficult to see because of an accumulation of dark staining tannins and resins. A few resin canals can be seen close to the hypodermal side of the mesophyll. Visit the BCC Bioscience Image featuring the Microscopic World of Plants. www.berkshirecc.edu/biologyimages Technical Questions:[email protected]
tangential section: Pinus stem magnification: 400x iron-alum hematoxylin and safranin stain Berkshire Community College Bioscience Image Library Gymnosperms like Pinus rely entirely on tracheids for water flow and mechanical support. True xylem vessels and wood parenchyma are lacking. While fibers are generally absent older stems may contain some fiber tracheids. The uniform wood of Pinus consists almost entirely of longitudinally oriented bands of narrow, pale staining tracheids interrupted by short bands of horizontally oriented xylem rays. Xylem rays, usually one cell thick and a few cells high, are composed of clear, thin walled parenchyma cells. The lumen of many tracheids is crossed by branched trabeculae. Tracheid side walls contain large circular bordered pits that function to move water from tracheid to tracheid while preventing air flow from embolized tracheids. The membrane of each bordered pit is marked by a pale, thin, porous outer margo and a thicker, darker, inner torus. Technical Questions:[email protected]
cross section: Pinus stem magnification: 100x Triarch quadruple stain Berkshire Community College Bioscience Image Library 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. Technical Questions:[email protected]
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cross section: Pinus needle magnification: 400x Triarch quadruple stain Berkshire Community College Bioscience Image Library A single layered epidermis of lignified cells is covered by a heavy waxy cuticle. Numerous sunken stomata are scattered over the entire epidermal surface. They are bounded by pairs of subsidiary cells, and open internally to a substomatal cavity and externally to a respiratory cavity or vestibule. The underlying hypodermis consists of several layers of thick-walled sclerenchyma, particularly well-developed at ridges. Visit the BCC Bioscience Image featuring the Microscopic World of Plants. www.berkshirecc.edu/biologyimages Technical Questions:[email protected]
Description of the evolution, biology, distribution, ecology, and uses of Pinus oocarpa (pino de colorado).
cross section: Pinus stem magnification: 400x Triarch quadruple stain Berkshire Community College Bioscience Image Library 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. Visit the BCC Bioscience Image featuring the Microscopic World of Plants. www.berkshirecc.edu/biologyimages Technical Questions:[email protected]
General Characters of Cycadofilicales / Pteridospermales / Seed Ferns. Morphology, Anatomy, Reproduction, Classification and Affinities of Pteridospermales
What is a gymnosperm? The word gymnosperm literally means "naked seed" (gymno=naked, sperm=seed). Gymnosperms have their seeds exposed unlike flowering plants, the angiosperms, which have their seeds enclosed in an ovary (i.e., fruit). The word angiosperm derives its meaning from angio=vessel, sperm=seed. Pine trees are the most often cited example of a gymnosperm. But what…
Hints and TeasersBrain Teasersby Lew Buller Is this tree a gymnosperm? What species is it? ...
Juniperus communis L. is a dioecious wind-pollinated gymnosperm, native for Luxembourg where its distribution is limited on sandstone and keuper marl. The shrub appears only in the centre of Luxemb…
These are seed-bearing fronds(?) of Cycas. The seeds are naked, hence the name Gymnosperm for the group. They are the first seed-bearing plants, it took millions of years perhaps to develop the cover for a seed and to get the juicy fruits of today :-)))
