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Chapter 22: Seed Plants 1: Plants Without Flowers ("Gymnosperms")
Chapter 22: Seed Plants 1: Plants Without Flowers ("Gymnosperms")
Concepts
Lignophytes
Spermatophytes
Gymnosperms
Angiosperms
Division Progymnospermophyta: Progymosperms
third group to evolve from trimerophytes was the now extinct progymnosperm
Aneurophytales
varied in stature from shrubs
to large trees up to 12 m tall
vascular cambium and secondary growth
Archaeopteridales
more derived progymnosperm was Archaeopteris in the order Archaeopteridales
Trees up to 8.4 m tall with abundant wood and secondary phloem
Evolution of Seeds
integument
micropyle
pollen chamber
microspores
Division Pteridospermophyta: Seed Ferns
The earliest seed ferns appeared in the upper devonian period- others appeared later
They were wood, wide, and very tall
Manoxylic
Division Coniferophyta: Conifers
familiar plants
Leaves of Agathis and Araucaria remain even on very old trunks
Long Shoots and Short Shoots
Simple cones
Compound Cones
Ovuliferous Scale
Suspensor
Proembryo
Division Cycadophyta: Cycads
frequently confused with either ferns or young palm trees because they have stout trunks with pinnately compound leaves
very old stems have only a small amount of wood
United states has only a few that can withstand freezing temperatures in winter
Division Cycadeoidophyta: Cycadeoids
are all extinct
contained both microsporophylls and megasporophylls
Division Ginkgophyta: Maidenhair Tree
contains a single living species
Ginkgo Biloba
"Broad Leaves"
Closely related to seed ferns
Division Gnetophyta
"Anthophytes"
contains three groups of enigmatic plants
Mostly vines or small shrubs with broad leaves
