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CHAPTER 22 - Coggle Diagram
CHAPTER 22
Division Cycadophyta: Cycads
were formerly more abundant and more diverse than they are today.
modern cycads are confused with either ferns or young palm trees because they have street trunks
Cycads are seed plants with a very long fossil history
tracheas are long and wide and rays are massive
hey typically grow very slowly and live very long
are highly prized ornamentals in the warmest parts of the united states
Division Coniferophyta: Conifers
they are diverse and all are trees of moderate to gigantic size
long shoots
consist of stems including their appendages, the leaves and lateral buds, flowering stems and flower buds
where leaves will develop
conifers are familiar plants
simple cones
a single short unbranched axis that bears microsporophylls
short shoots
produce the familiar long needle leaves
are reproductive
compound cones
Most living conifers have a seed cone that is interpreted as a compound
each consisting of a shoot with axillary buds
cone bracts
short axis bears leaves
each bracts has an axillary bud that bears the megasporophylls
Division Ginkgophyta: Maidenhair Tree
looks very much like a large dicot tree with a stout trunk and many branches
Ginkgos
have both short shoots, which bear most of the leaves
is dioecious and gymnospermous, but cones are not produced
tree itself is beautiful and is a popular ornamental because the leaves turn yellow in the autumn
s the only living species in the division Ginkgophyta
the latter species became extinct during the Pliocene Epoch
It is a member of a very old genus, with some fossils dating back 270 million years
Division Progymnospermphyta: Seed Ferns
progymnosperms gave rise to another line of gymnospermous plants in addition to the conifers
seed fern wood was manoxylic, much softer and less dense than wood of conifers and progymnosperms
the stratigraphically oldest known examples belong to the Middle Devonian
leaves of seed ferns were similar to those of true ferns in overall organization
Division Gnetophyta
gnetums are mostly vines or small shrubs with broad leaves similar to those of dicot
they are native to Southeast Asia, tropical Africa and the Amazon Basin
contains three groups of enigmatic plants
Ephedra
about 40 species
Welwitschia mirabilis
the only species in the genius
Gnetum
is a family of gymnosperms with 30 species
all three genera are unusual in being gymnosperms with vessels in their wood
anthophytes
are a grouping of plant taxa bearing flower-like reproductive structures.
having evolved in parallel
Division Cycadeoidophyta: Cycadeoids
the cycadeoids had vegetative features almost identical to those of cycads
differ only in the differentiation of stomatal complexes and in leaf trace organization
cycadeoids would never be considered distinct from cycads
individuals cones of cycadeoids contained both microsporophyll and megasporophylls
Division Progymnospermphyta: Progymnosperms
Archaeoperitales
They reproduced with spores rather than seeds
these were trees up to 8.4 m tall with abundant wood and secondary phloem
reproduction was heterosporous
megaspores were released from the sporangia, not retained
Evolution of Seeds
microspores were evolving into pollen grains
spores were trapped in a sporangium attached to leaves or wood during fossilization
Aneurophytales
contains the more relictual progymnosperms
they all had a vascular cambium and secondary growth
a class of progymnosperms
The genus is primarily known from records of two well-known species found in mostly
