F ... 22 - Gymnosperms Flashcards
gymnosperms
“naked seed” - lack protective enclosure
fertilization without water (wind)
secondary growth (wood)
why are seeds successful?
protects embryo
provides nutrients to embryo during dev
define seed
mature ovule containing embryo
ovule consists of
megasporangium enveloped by integuments with micropyle end
integuments dev into ___
seed coat
evolutionary features of ovule maturation into seed
- integuments envelops the megasporangium that no longer releases spores
- reduction of megaspore mother cells to one per megasporangium ( 1/4 survive )
- formation and dev of retained (non-free living) megagametophyte and megasporangium
gymnosperm pollination occurs ___ by ___
passively, wind
4 phyla of gymnosperms
- Coniferophyta (conifers)
- Cycadophyta (cycads)
- Ginkophyta (ginko)
- Gnetophyta (gnetophytes)
Coniferophyta
conifers
- pines (monoecious), firs, spruce
- largest gymno group
- no motile sperm (pollen tube)
- needle-like leaves
progymnosperms
secondary growth (wood) no seeds, reprod by spores
cones
staminate male cones ovulate female cones open 'naked' scales no flower or fruit micro/megasporangia in separate cones (male low, female high)
conifer fertilization
one sperm nucleus fuses with egg to form zygote
other sperm nucleus degenerates (no endosperm)
cycads have ___ sperm that dev withinand are carried to egg by ___.
multiflagellate sperm
pollen tube
Cycadophyta
palm-like plants
motile sperm
megaphyll leaf
male and female plants
Ginkgophyta
only extant species (Ginkgo biloba)
motile sperm (no pollen tube)
fan-shaped leaves
male and female plants
