Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 22 Seed Plants I: Seed Plants Without Flowers ("…
Chapter 22 Seed Plants I: Seed Plants Without Flowers ("Gymnosperms")
Concepts
lignophytes
synonym for a plant develops wood
used as an informal name for the clade woody plants
spermatophytes
plants produce seeds
Alternative:
vascular cryptogams
gymnosperms
"naked ovules"
located on flat sporophylls
example
Pine cones
angiosperms
flowering plants
with carpels
believed to be sporophylls form a tube-like
closed structure
fruits are mature carperls
division of living seed plants
division Cycadophyta
#
division Coniferophyta
#
division Ginkgophyta
division Gnetophyta
#
division Magnoliophyta
Division Progymnospermophyta: Progymnosperms
Aneurophytales
contains the more relictual progymnosperms
Aneurophyton
Protopteridium
Proteokalon
Tetraxylopteris
Triloboxylon
Eospermatopteris
further resembled trimerophytes in having little webbing between their ultimate branches
Archaeopteridales
more derived progymnosperms was Archaeopteris
trees up to 8.4m tall with abundant wood
secondary phloem
heterosporous reproduction in archaeopterids
Evolution of Seeds
integument
megasporangium was surrounded by a layer of tissue
projected upward
micropyle
hole in integument that permitted the sperm cells to swim to the egg after developed into megagamtophyte
produced eggs
progymnosperms
third group to evolve from trimerophytes
rise later to
conifers
cycads
other gymnosperms
Division Pteridospermophyta: Seed Ferns
earliest seed ferns
upper Devonian period
other appeared later
progymnosperms gave rise to another line of gymnospermous plants in addition to the conifers
cycadophytes
classified as three division
Pteridospermophyta
seed ferns
all extinct
Cycadophyta
cycads
extant
Cycadeoidophyta
cycadeoids
all extinct
pteridosperms are thought have evolved from the Aneurophytales
b/c earliest seed ferns
Stenomyelon
Division Coniferophyta: Conifers
conifers
familiar plants
all trees of moderate to gigantic size
giant redwoods of CA
Sequoiadendron giganteum
simple cones
pollen cones
single short unbranched axis that bears microsporophylls
compound cones
each consisting of a shoot with axillary buds
cone bracts
short axis bears leaves
ovuliferous scale
axillary bud is microscopic
its megasporophylls are fused laterally
Division Cycadophyta: Cycads
modern cycads are frequently confused with either ferns or young palm trees
have stout trunks with pinnately compound leaves
most cycads are short plant less than 1 or 2 m tall
Macrozamia can reach heights of 18m
Division Cycadeoidophyta: Cycadeoids
had vegetative features almost identical to those of cycads
two groups differ only in subtle details of the differentiation of stomatal complexes
Division Ginkgophyta: Maidenhair Tree
#
division contains a single living species
Ginkgo biloba
unusual to erect an entire division for a single species
G. biloba is itself unusual
maidenhair tree
Division Gnetophyta
anthophytes
two sister clades with a common ancestor
certain aspects of their anatomy
reproduction have been interpreted as indicate that gnetophytes
contains three groups of enigmatic plants
Gnetum with 30 species
Ephedra with about 40 species
Welwitschia mirabilis, the only species in the genus
