Please enable JavaScript.
Coggle requires JavaScript to display documents.
Ch. 22 Seed Plants1: Seed Plants Without Flowers ("Gymnosperms")…
Ch. 22 Seed Plants1: Seed Plants Without Flowers ("Gymnosperms")
Concepts
lignophytes
monophyletic group of woody plants
spermatophytes
seed plants
monoxylic vs. pycnoxylic wood
mano= soft, spongy, parenchymatous wood
pycno= hard, strong wood (little parenchyma)
Gymnosperms
"naked ovules"
located on flat sporophylls
pine cones
Angiosperms
flowering plants
tube-like sporophylls
Division Progymnospermophyta: Progymnosperms
Aneurophytales
contains more relictual progymnosperms
further resembled trimerophytes
little webbing between branches
Archeopteridales
more derived progymnosperm
tall trees with abundant wood and secondary phloem
Evolution of Seeds
integument
layer of tissue projected upward
micropyle
hole in the integument
permitted sperm cells to swim to egg after development
pollen chamber
holding area for microspores
Define:
some gave rise later to conifers, cycads, and other gymnosperms
Division Pteridospermophyta: Seed Ferns
#
earliest appeared in the upper devonian period
later species, most central cells of stem were parenchyma
long-lived vascular cambium
Division Coniferophyta: Conifers
shoots
long
tiny papery leaves
short
long needle leaves
cones
simple
pollen cones
compound
shoot with axillary buds
cone bracts
axillary bud has megasporophylls
fused called ovuliferous scale
zygote
suspensor
first cells elongate
proembryo
develop into the embryo
Division Cycadophyta: Cycads
foliage leaves do not bear ovules
#
aprox. 100 species now
much more in earlier times
very short can be confused with young palm trees
Division Cycadeoidophyta: Cycadeoids
#
all extinct
cones
had megasporophylls and microsporophylls
Division Gnetophyta
anthophytes
if two formed a group
three groups of enigmatic plants
Gnetum
30 species
Ephedra
40 species
Welwitschia mirabilis
only species in genus
Division Ginkgophyta: Maidenhair Tree
lacks vessels and axial parenchyma
have short and long shoots
genders
male
microsporangiate
female
megasprangiate
thought to have evolved from
produce these and seed cones
almost identical
