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UNDERSTANDING GYMNOSPERMS

UNDERSTANDING GYMNOSPERMS. JRMG 2008-2009. What are GYMNOSPERMS?. gymnos - naked + spermae - seed have seeds (not fruits or flowers) developed (Paleozoic Era) dominant: Mesozoic Era (early ) heterosporous seed ferns Cone bearing plants. GYMNOSPERMS. 700 living species

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UNDERSTANDING GYMNOSPERMS

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  1. UNDERSTANDINGGYMNOSPERMS JRMG 2008-2009

  2. What are GYMNOSPERMS? • gymnos- naked + spermae - seed • have seeds (not fruits or flowers) • developed (Paleozoic Era) • dominant: Mesozoic Era (early ) • heterosporous seed ferns • Cone bearing plants

  3. GYMNOSPERMS • 700 living species • conifers (such as pines and spruce) • cycads (such as the sago palm, Cycasrevoluta) • ginkgos (the maidenhair tree, Ginkgo biloba) • gnetophytes (such as Mormon tea, Ephedra)

  4. DIVISION GNETOPHYTA • 70 species (3 genera) • Welwitschia • two huge leathery leaves • Ephedra • Mormon tree • Gnetum • leaves angiosperm-like • vessels in the xylem • considered an angiosperm characteristic

  5. DIVISION GNETOPHYTA • have some angiosperm-like features • Cladistic analyses support placement of the gnetales (or some portion of them) as outgroups for the flowering plants

  6. Welwitschia mirabilis

  7. DIVISION CYCADOPHYTA • pinnate leaves and circinatevernation • heterosporous • cones are unisexual • dioecious • free-swimming sperm

  8. DIVISION GINKGOPHYTA • Ginkgo biloba • the maidenhair tree • dioecious • males are more commonly planted • females produce seeds that have a nasty odor • pollination is by wind • swimming sperm

  9. DIVISION CONIFEROPHYTA • Most common gymnosperms • Pines, spruces, firs, cedars, sequoias, redwood and yews • Can live more than 4000 y.o.

  10. DIVISION CONIFEROPHYTA • evergreen • needle-like leaves • Needles have a thick cuticle • sunken stomates • reduced surface area

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