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Ch. 22 Seed plants w/o flowers ("Gymnosperms"), explaining long…
Ch. 22 Seed plants w/o flowers ("Gymnosperms")
Progymnosperms
Archaeopteridales
trees
secondary phloem
stems siphonostele
reproduction = heterosporous
Evolution of Seeds
micropyle
hole in integument
allows sperm to swim to egg
pollen chamber
top of megasporangium
holding area
where megaspores settle
integument
layer of tissue around megasporangium
projected upward
Aneurophytales
vary from shrubs to trees
vascular cambium
secondary growth
primary xylem protostele
Division Progymnospermophyta
progymnosperms
#
evolve from trimerophytes
rise to conifers, cycads, etc
Seed Ferns
Division Pteridospermophyta
seed ferns
all extinct
appeared in Upper Devonian Period
vascular bundle around pith
vascular cambium
tracheas long and wide
Conifers
Division Coniferophyta
long shoots
tiny papery leaves
short shoots
long needle leaves
simple cones
pollen cones
short unbranched axis
microsporophylls
compound cones
pollen cones
shoot w axillary buds
short axis bears cone bracts
cone bracts
axillary buds w megasporophyll
ovuliferous scale
megasporophylls fused laterally
suspensor
pushes other cells into megagametophyte
proembryo
other cells
develop into embryo
Cycads
Division Cycadophyta
most short
exception Macrozamia
produce seed and pollen cones
small manoxylic wood
parenchymatous
thick cortex w secretory ducts
Cycadeoids
#
Division Cycadeoidophytea
almost identical to cycads
all extinct
cones contain megasporophylls and microsporophylls
Maidenhair Tree
Division Ginkgophyta
one species Ginkgo biloba
lacks vessels
lacks axial parenchyma
have short & long shoots
#
reproduction
dioecious
gymnospermous
no cones
Division Gnetophyta
vessels in wood
3 groups of enigmatic plants
Ephedra
Welwitschia mirabilis
Gnetum
compound cones
#
small cone bracts
explaining long and short shoots
gave rise to conifers
both contain compound cones
nearly identical
ex. of aneurophytales variation
https://almerja.com/medea/images/ximage005_241.jpg.pagespeed.ic.iiZr5NMHUY.jpg
ex. of a conifer tree
https://i.ytimg.com/vi/X1pAPZeQcmc/maxresdefault.jpg
showing extinct seed fern
https://images.fineartamerica.com/images-medium-large-5/seed-fern-alethopteris-aquilinus-fossil-natural-history-museum-londonscience-photo-library.jpg
displaying Maidenhair Tree
https://hgic.clemson.edu/wp-content/uploads/2018/02/word-image-13.jpeg
ex. of a cycad
https://animals.sandiegozoo.org/sites/default/files/2016-11/cycad-T11_0809_037.jpg
