Gymnosperms

19 flashcards · Biology · by Grayson Lauer

1. gymnosperm

   a vascular plant that produces naked seeds (those exposed to the atmosphere) (no flowers, exclusively woody, seeds spread via wind, no xylem vessels)

2. strobili

   cones (can be ovulate or staminate) (singular strobilus)

3. microsporophyll

   a cone scale that bears microsporangia and microsporocytes

4. microsporangium

   a pollen sac

5. microsporocytes

   2N cells in microsporangia that undergo meiosis, forming pollen

6. megasporophyll

   a cone scale that bears megasporangia

7. ovule

   a specialized megasporangium, matures into a seed

8. megasporocyte (megaspore mother cell)

   a female spore, 2N cell that undergoes meiosis, forming an egg

9. micropyle

   a pore receptive to pollination, located at the end of the ovule

10. double fertilization

    a single pollen grain contains two sperm cells, one of which fuses with the egg and the other breaks down and is used for nutrition for the seed

11. examples of gymnosperms

    cycads, conifers, ginkgo; 500+ species exist today

12. integument

    the outermost layer of the ovule, covers and offers protection for the inner tissues, forms the seed coat at maturity (closes when the pollen meets the egg)

13. sporophyte

    an adult tree or shrub that bears staminate and ovulate strobili

14. phylocode classifications (clades) of gymnosperms

    /Cycadophyta, /Gnetophyta, /Ginkgo, /Coniferae

15. /Cycadophyta

    motile sperm cells, pinnate leaves, dioecious, palm-like trees or shrubs

16. /Ginkgo

    motile sperm cells, simple fan-shaped leaves, dichotomous veination, dioecious, trees (only contains one species) (female cones smell like moldy cheese gym lockers)

17. /Coniferae

    non-motile sperm cells, trees or shrubs, simple staminate strobili (includes pine family, yew family, and cypress family)

18. /Gnetophyta

    compound staminate strobili, not resinous (includes Gnetaceae (30 species), Welwitschiaceae (1 species), and Ephedraceae (40 species))

19. gymnosperms origin

    appeared in the Carboniferous (Cretaceous) period, ~360 mya, and became the dominate flora of the earth