Please enable JavaScript.
Coggle requires JavaScript to display documents.
Seed Plants I: Seed Plants W/O flowers (Division Ginkgophyta (Wood is…
Seed Plants I: Seed Plants W/O flowers
Concepts
Lignophytes
Gave rise to a monophyletic group
Clade that contains a woody plant
Spermatophytes
Existed after the origin of wood
Before the seeds were trees
reproduced with spores similar to ferns
Produce seeds
Manoxylic Wood
contains significant amounts of axial parenchyma
Such as the cycads
contain soft spongy wood
large compound leaves
Radically symmetrical seeds
Gymnosperms
Common name for naked seeds
All seed plants not angiosperms
Ovules located on flat sporophylls
Ex) Pine cones
Pyncoxylic Wood
Wood with little or no axial parenchyma
Consists of strong
Hard woods
Opposite of manoxylic wood
Such as gymnosperms and progymnosperms
Angiosperms
Flowering plants
Those with carpels
Believed to be sporophylls
form tube like closed structures
fruits are mature carpels
Division Pteridospermophyta
Seed Ferns
Appear in the upper Devonian Period
Fern with seeds apart of reproductive cycle
Seeds have been originated twice
Seed Fern Wood
Manoxylic
Softer and less dense
Classified by 3 division
Cycadophyta
Cycads
Extant
Cycadeoidophyta
Cycadeoids
All Extinct
Pteridospermophyta
Seeds ferns
All Extinct
Division Ginkgophyta
Contains only a single living species
Ginkgo biloba
Also known as the maidenhair tree
Looks similar to a large dicot tree
with a stout trunk
several branches
Wood is similar to conifers
lacks vessels
lacks axial parenchyma
Has broad leaves
Dichotomously branched veins
similar to seed ferns
Contain both short and long shoots
short shoots bear almost all leaves
long shoots also bear few leaves
Reproduction
Dioecious
gymnospermous
Cones are not produced
Ovules occur in pairs
towards the end of the short stalk
Completely unprotected at maturity
Division Coniferophyta
two types of shoots
Long Shoots
Tiny Papery Leaves occur
Short Shoots
Familiar long needle leaves
Two types of Pines
Seed Cones
Also known as compound cones
Each consists of a shoot with axillary buds
Bears cone bracts not sporophytes
Each Bract has an axillary bud
bears the megasporophylls
More complex than pollen cones
Pollen Cones
Also known simple cones
single short unbranched axis
bears microsporophylls
Microspore mother cells
undergoes meiosis
Form microspores
Each develops endosporically
Ovuliferous Scale
Megasporophyll fused laterally to create <-
Still distinct and can be seen
In Larch, Fir, and Douglas
It is fused to the bract
Suspensor
first cells elongate
Push the other cells deep
Into the megagametophyte
Zygote do not immediately form an embryo
Proembryo
Develop into the embryo
No double fertilization
Female gametophyte continues to grow
Acts as a haploid nutritive tissue
Division Progymnospermophyta
Archaeopteridales
abundant wood and primary xylem
Stems of archaeopteris
siphonostele
pith surrounded by
ring of primary xylem bundles
Similar to modern conifers and dicots
Evolution of Seeds
Integument
layer of tissue that surrounds the megasporangium
Micropyle
a hole in the integument
permitted the sperm cells to get to the egg
After the megaspore had developed to Megagamterophyte
Produced an egg
Pollen Chamber
also known as a holding area
Place where microspores settled
Fused together and to the megasporangium
space at top of megasporangium
Aneurophytales
Contains more relictual pro gymnosperms
Protopteridium
Proteokalon
Aneurophyton
Tetraxylopteris
Vary in stature
contain vascular cambium/secondary growth
Primary xylem was protostele
similar to rhyniophytes/trimerophytes
Progymnosperms
Now extinct
Some gave rise to later trees
Cycads
Other Gymnosperms
Conifers
Also developed megaphyllous leaves
Evolution of vascular cambium
Capable of undergoing radial division
unlimited growth potential
Capable of producing
secondary xylem
secondary phloem
Division Cycadeoidophyta
#
All are extinct
Vegetative features similar to cycads
differences between cycads
stomatal complexes
Leaf trace organization
Individual cones
contain both
Microsporophylls
Megasporophylls
Each Ovule has a stalk
megasporagnium is surrounds by integument
Extended out into long micropyle
Division Gnetophyta
contains 3 groups of enigmatic plants
Ephedra
Apppox. 40 species
Tough shrubs and bushes
Leaves are reduced
Scale like
Common in desert regions
Southwestern US
Dry mountains in South America
Northern Mexico
Welwitschia mirabilis
this is the only species in genus
Exist only in desert in South Africa
Short wide stems
only two leaves
Leaves grow perennially
from a basal meristem
Becoming increasingly longer
Gnetum
Approx. 30 species
Mostly vines or small shrubs
Have broad leaves
similar to dicots
Native to 3 places
South East Asia
Tropical Africa
Amazon Basin
Division Cycadophyta
#
#
Frequently confused with ferns/young palm trees
Due to short trunks
Pinnately compound leaves
Size
Typically short plants(1-2 M)
may grow up to 18M tall
Trunk
Covered in bark
Persistent leaf bases
remain on plant
Even after lamina
and Petiole have abscised
Internally
Stems similar to seeds ferns
Have a thick cortex
containing a secretory ducts
Surrounds a small amount of manoxylic wood
Tracheids
long and wide
rays are massive
Leaves
do not bear ovules
produce seed cones and pollen cones
Each on separate plants
Always dioecious
cycads contain manoxylic woods
Cycadeoids and Cycads are closely related in several ways
Cycads are similar to ferns in classification
