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Seed Plants Without Flowers, image, image, image, Seed Ferns have…
Seed Plants Without Flowers
Concepts
disadvantage of vascular cryptograms lifecycle
temporarily dependent on tiny gametophyte for start of life
many new sporophytes perish
free living gametophytes
develop on soil
retained gametophytes
develop high on plant in strobili
lignophytes
woody plants
spermatophytes
seed plants
manoxylic wood
#
soft
spongy, parenchymatous wood
large compound leaves
pycnoxylic wood
hard, strong, little parenchyma
small, simple, flat leaves
gymnosperms
#
naked ovules
pine cones
Angiosperms
flowering plants
fruits: mature carpels
Division Progymnospermophyta
Progymnosperms
now extinct
evolved from trimerophytes
gave rise to conifers, cycads, and other gymnosperms
megaphyllous leaves
vascular cambium: secondary xylem and secondary phloem
strong wood, effective conduction
cork cambium
Proteokalon
Triloboxylon
true woody trees
simple reproduction
Aneurophytales
shrubs to large trees
#
vascular cambium and secondary growth
having little webbing between ultimate branches
Archaeopteridales
heterosporous
abundant wood and secondary phloem
seeds not produced
Evolution of Seeds
megasporangium
surrounded by integument
microphyle, hole in integument permitting sperm cell flowing in
pollen chamber
holding area
Division Pteridospermophyta
seed ferns
earliest
bore seeds
resembled modern trees, some vines
ring of vascular bundles, surrounding a pith
manoxylic
softer wood
occurs in cycads and cycadeoids
leaves of seed ferns
like regular ferns, just bore seeds
Division Coniferophyta
Conifers
never vines, herbs, or annuals
leaves simple needs or scales
leaves are perennials
pollen cones and seed cones
woody seed cones
Pines
long shoots
tiny papery leaves
short shoots
long needle leaves
pollen cones and seed cones
simple cones
short unbranched axis bears microsporophyll's
gametophytes spread by wind
Seed cones
more complex than pollen cones
compound cones
shoot with axillary buds
cone bracts not sporophylls
ovuliferous scale
Zygote
does not immediately form an embryo in conifers
elongate as a suspensor
pushes cell deep into the megagametophyte
proembryo
develops into embryo
no double fertilization
Division Cycadophyta
Cycads
short plants
leaves do not bear ovules
produce seed and pollen cones
dioecious
almost all tropical
Division Cycadeoidophyta
Cycadeoids
all extinct
vegetative features
cones contain both microsporophylls and megasporophylls
each ovule had a stalk
microsporophyll
cup shaped and contained numerous microsporangia
Division Ginkgophyta
Ginko
short and long shoots
bear most of the leaves
dioecious and gymnospermous
cones not produced
ovules in pairs, end of short stalk
unknown ancestors
Division Gnetophyta
three groups of enigmatic plants
Ephedra
tough shrubs and brushes
desert region
Welwitschia mirabilis
short wide stem and two leaves
Gnetum
small shrubs, large leaves
Seed Ferns have manoxylic wood
Both Gnetum and Aneurophytales can be shrubs
Ginko trees are gymnosperms
