_________ thickening

1
Seed plants

• _________ thickening
• Bipolar embryos
• Seeds

2
Archaeopteris (fossil)Homospory 2º thickening
3
Seed Habit

• Fertilization happens in the megasporangium
• Ovule/Seed a megasporangium with an integument
  
• Dormant _________ dispersed within the seed

4
The two seed plant clades

• Gymnosperms
• Cycads 100 spp. Motile sperm
• Ginkgophytes 1 spp. Motile sperm
• Conifers 500 spp. Nonmotile sperm
• Gnetophytes 70 species. Nonmotile sperm
• Angiosperms 250,000 species. ________ sperm

5
Seed plant phylogeny
angiosperms
cycads
conifers
gnetophytes
Ginkgo
Loss of motile sperm
Loss of motile sperm
(Your textbook is out of date)
6
Cycads

• Seed and pollen cones on different plants
  (______)
• Motile sperm
• Often beetle pollinated

Cycas Megasporangiate
Cycas Microsporangiate
7
Ginkgophytes (Ginkgo biloba)
seeds

• ________

Ciliate sperm
8
Ginkgo and Cycads have _____ sperm
Megasporangium wall
Microgametophyte
Pollen tubes
9
Gnetophytes

• No motile sperm
• May be animal _________
• Three distinct genera

Ephedra (35 spp.)
Welwitschia (1 spp.)
Gnetum (30 spp.)
10
Conifers

• _________ cones
• Dioecious or monoecious plants
• Non-motile sperm