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Chapter 22: Seed Plants I: Seed Plants Without Flowers (Division…
Chapter 22: Seed Plants I: Seed Plants Without Flowers
Division Pteridospermophyta: Seed Ferns
seed ferns
Upper Devonian Period
Division Progymnospermophyta: Progymnosperms
Archaeopteridales
A. macilenta
Evolution of Seeds
Chauleria
Middle Devonian Period 390 Million Years Ago
Archaeosperma arnoldii
integument
micropyle
pollen chamber
Aneurophytales
Eospermatopteris
Progymnosperms
Division cycadophyta: Cycads
less than 1 or 2m tall
Stout trunks
pinnately compound leaves
Division Coniferophyta: Conifers
Long shoots
Short shoots
Simple cones
seed cones
compound cones
cone bracts
ovuliferous scale
suspensor
megagametophyte
proembryo
Division Cycadeoidophyta: Cycadeoids
all extinct
almost identical to cycads
Division Ginkgophyta: Maidenhair Tree
Single living species
Ginkgo biloba "maidenhair tree"
dioecious and gymnospermous
1.5 to 2.0m in diameter
unknown ancestory
Division Gnetophyta
Ephedra
40 species
desert regions in northern Mexico and southwestern United States and dry mountains in South America
reduced scale like leaves
Welwitschia mirabilis
only one with a genus
deserts of South Africa
short, wide stem with only two leaves
Gnetum
30 species
Native to Southeast Asia, tropical Africa, and the Amazon Basin.
mostly vines or small shrubs
