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Seed Plants I: Gymnosperms (Pycnoxylic wod (hard, strong wood with little…
Seed Plants I: Gymnosperms
Cladogram of seed plants
Gymnosperms
plants w/ ovules on flat sporophylls
Ex. Pine cones
Lignophytes
Monophyletic group of woody plants
Spermatophytes
Seed plants
Seeds originated after wood
Angiosperms
Flowering plants w/ carpels
Fruits are mature carpels
Manoxylic wood
soft, spongy, parenchymatous wood produced by plants
large, compound leaves and radially symmetrical seeds
Pycnoxylic wod
hard, strong wood with little parenchyma
small, simple leaves and flattened seeds
Occurs in conifers
Progymnosperms
Gave rise to conifers, cycads and other gymnosperms
Micropyle
a hole in the integument that permits sperm cells to swim to the egg after the megaspore had developed into a megametophyte and had produced eggs
Pollen chamber
where microspores settle
Integument
a layer of tissue
Seed ferns
appeared in the Upper Devonian period
form a grade rather than a clade
Pines
have two types of shoots
Long shoot
Tiny papery leaves
In the axials are
Short shoots
produce the long needle leaves
Pines have both
pollen cones
and
seed cones
Pollen cones are
simple cones
w/ single short unbranched axis that bear mirosporophylls
Seed cones are
compound cones
consists of a shoot with axillary buds
the short axis bears leaves called
cone bracts
rather than sporophylls
Each bract has an axillary bud bearing megasporophylls
megasporophylls are fused later forming an
ovuliferous scale
