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Seed Plants 1: Seed Plants Without Flowers ("Gymnosperms")…
Seed Plants 1: Seed Plants Without Flowers ("Gymnosperms")
Concepts
life cycle of vascular cryptogams
alternation of independent, heteromorphic generations
disadvantage
new sporophyte
temporarily dependent on gametophyte
has identical genes of maternal sporophyte
evolution of seeds
vascular cambium
lycophytes/equisetophytes
monophyletic plants
lingophytes
seed plants
spermatophytes
2 major suites of characters
soft, spongy, parenchymatous wood
manoxylc wood
cycads
hard, strong little parenchyma
pycnoxylic wood
conifers
all seed plants
classification from 1800s
Spermatophyta
Gynospermae
gymnosperms
naked ovules
ovules on flat sporophylls
pine cones
group should be abandoned
Angiospermae
angiosperms
flowering plants
mature carpels
1 more item...
classification used today
division Cycadophyta
division Coniferophyta
division Ginkgophyta
division Gnetophyta
division Magnoliophyta
Division Progymnospermphyta: Progymnosperms
Aneurphytales
mroe relictual species
Aneuophyton
Protopteridium
Proteokalon
Tetraxylopteris
Triloboxylon
Eospermatopteris
shrubs
large trees
vascular cambium
secondary growth
protostele
#
#
Archaepteridales
order Archaeopteridales
Archaeopteris
8.4 m tall
abundant wood
secondary phloen
stems had siphonostele
modern conifers/dicots
fronds
branched "leaflets"
reproduction
heterosporous
megaspores released
Evolution of Seeds
free-sporing species
spores trapped in sporangium on
leaves
wood
spores cannot be identified w/ gametophyte
Middle Devonian Period
species with heterospory
Chauleria
Upper Devonian Period
Archaeosperma arnoldii
one mother cell
one large megaspore w/ 3 aborted cells
megasporanium was surrounded by
integument
layer of tissue
hole
micropyle
similar to pollen chamber
Trimerophytes
evolved from rhyniophytes
pseudomonopodial branching
progymnosperms
now extinct
gave rise to
conifers
cycads
other gymnosperms
megaphyllous leaves
vascular cambium
secondary growth
secondary phloem
produced true woody trees
Triloboxylon
Proteokalon
no seeds/ovule precursors
Division Pteridospermophyta:Seed Ferns
cycadophytes
Pteridospermophyta
seed ferns
all extinct
Cycadophyta
cycads
extant
Cycadeoidophyta
cycadeoiods
all extinct
Upper Devonian Period
#
seed ferns
formed a grade
woody trees w/ seeds
long-lived vascular cambium
xylem
phloem
manoxylic wood
#
leaves
large
compound
planar
Stenomyelon
#
Pteridosperms
Aneurophytales
Division Coniferophyta: Conifers
diverse
moderate to gigantic size
redwoods of California
Sequoiadendron giganteum
not
vines
herbs
annuals
no bulbs or rhizomes
leaves are simple needles/scales
perennial
live for many years
venation is simple
one/two veins
endodermis
transfusion tissue
parenchyma cells
trachieds
all have
pollen cones
simple cones
short, unbranched axis
microsporophylls
seed cones
fruits of flowering plants
Juniperus
Podocarpus
herbs
shrubs
small trees
compound cones
short axis
cone bracts
leaves
axillary bud
megasporophylls
ovuliferous scale
3 more items...
microscopic
pines
monopodial
tracheids
annual rings
spring wood
summer wood
rays
resin canals
phloem
cork cambium
shoots
long shoots
papery leaves
short shoots
long needles
conifer pollen
suspensor
pushes cells deeper in megagametophyte
proembryo
make the embryo
same as angiosperm embryo
flowering plant
Division Cycadophyta: Cycads
modern cycads
stout trunks
covered with bark
persistent leaf bases
pinnately compound leaves
short
can reach to 18 m tall
Macrozamia
similar to seed ferns
#
thick cortex
secretory ducts
manoxylic wood
#
tracheids
long
wide
rays
massive
permanent pith
pollen cones
#
spirally arranged
shield-shaped microsporphylls
microsporangium
seed cones
#
relictual
large
loose, aggresive
large ovules
almost all tropical
unusual distribution
Division Cycadeoidophyta: Cycadeiods
#
all extinct
identical to cycads
2 groups differ in
stomatal complexes
leaf trace organization
cones contribute
microsporpyhlls
cup-shaped
numerous microsporangium
megasporophylls
megasporangium
integument
micropyle
Division Ginkgophyta: Maidenhair Tree
single living species
Ginkgo biloba
large dicot tree
stout trunk
many branches
wood is like conifers
no vessles/axial parenchyma
broad leaves
dichotomously branched veins
short shoots and long shoots
reproduction
dioecious
male
female
gymnospermous
no cones
ovules
pollen is produced by catkin
Division Gentophyta
3 groups of enigmatic plants
Gnetum
30 species
mostly
vines
shrubs
broad leaves
Ephedra
40 species
tough
shurbs
bushes
reduced, scale-like leaves
Welwitschia mirabillis
short, wide stems
only 2 leaves
perennially from basal meristem
increasing longer
seed cones
#
compound
extra layer of tissue around ovules
pollen cones
#
compound
small bracts
anthophytes
