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Seed Plants Without Flowers (Gymnosperms) - Coggle Diagram
Seed Plants Without Flowers (Gymnosperms)
Evolution of seed plants
Development of seeds
Retaining of megaspore
Megasporophylls grouped in "cones"
Microspores moved by wind
Dropped onto megasporangiate cone
Produced 1st seed plants
Earliest to latest plants
Pteridospermophyta
Cordaitales
Several descendant lines
Cycads and
Ginkgos
Motile, swimming sperm
Conifers and angiosperms
Nonmotile sperm
Development of vascular cambium
Radial longitudinal division
Produced massive trees
Two suites of characters
In cycads and relatives
Manoxylic wood
Soft, spongy, parenchymatous
Large, compound leaves
Radially symmetrical seeds
In conifers and relatives
Pycnoxylic wood
Hard, strong, little parenchyma
Small, simple leaves
Flattened seeds
Bidirectionally symmetrical
Division Progymnospermophyta
Progymnosperms
Ancestors of gymnosperms
Morphology
Megaphyllous leaves
Vascular cambium
Radial longitudinal divisions
Secondary xylem and phloem
Elongate tracheids
Circular bordered pits
Rays
Tall and uniseriate
Cork cambium in some
No seeds or ovules
Megaspores shed
Longitudinal slits
Two orders
Aneurophytales
Contains more relictual plants
Vascular cambium
Secondary growth
Protostele
No "leaves"
Little webbing between branches
Archaeopteridales
Leaflets
Spirally arranged simple leaves
Few species with webbing
Partial webbing
A. macilenta
Complete webbing
A. halliana
and
A. obtusa
Siphonostele
Heterosporous
No seeds
Sporangia terminal on branches
Megaspores released
Trees
Abundant wood
Secondary phloem
Evolution of seeds
Steps in development of seeds
Later species of progymnosperms
Development of integument
One megasporangium
Became surrounded by telomes
Fused together
1 more item...
Development of pollen chamber
Micropyle
Hole sperm swim through
Fusion of telomes
1 more item...
Division Pteridospermophyta
Seed ferns
Part of cycadophytes
Characteristics
Fern-like foliage
Bore seeds
Woody plants
Stem morphology
Three-ribbed protostele
Protostele reveals possible ancestry
Ring of vascular bundles
Surrounded pith
Long-lived vascular cambium
Produced xylem and phloem
Tracheids
Longer/wider than progymnosperm's
Rays
Tall and many cells wide
Cortex
Inner cortex
Secretory ducts
Outer cortex
Thick
Radial plates of sclerenchyma
Manoxylic wood
Leaves
Similar to true ferns
Large, compound, and planar
Bore seeds
Division Coniferophyta
Conifers
Only trees
Leaves
Perennial
Veins
Transfusion tissue
Transfusion parenchyma
Transfusion tracheids
Facilitates transfer
Mesophyll tissue outside endodermis
Vascular tissues
Simple needles or scales
Stems/wood
Lack vessels
Lack sieve tubes
Rays
Ray parenchyma
Ray tracheids
Lacks axial parenchyma
Shoots
Two types
Long shoots
Have tiny, papery leaves
Short shoots
Have long needle leaves
Cones
Simple cones
Pollen cones
Single short unbranched axis
Bear microsporophylls
Compound cones
Seed cones
Shoot with axillary buds
Cone bracts
Has axillary bud
Bears megasporophylls
Ovuliferous scale
Fusion of megasporophylls
In modern conifers
Reproduction
One megaspore survives
Development of megagametophyte
2-3 archegonia form
Each surround 1 large egg
Conifer pollen arrives
1 more item...
Division Cycadophyta
Cycads
Morphology
Pinnately compound leaves
Most are short
Exception is
Macrozamia
Can reach 18m tall
Stout trunks
Covered with leaf bases
Bark
Stems
Manoxylic wood
Thick cortex
Secretory ducts
Reproduction
Both dioecious with separate cones
Dioecious
Seed cones
Pinnately compound megasporophylls
Large, vascularized megasporangium
Vascularized integument
Pollen cones
Spirally arranged microsporophylls
Clusters of microsporangia
Germination produces pollen tube
Division Cycadeoidophyta
Cycadeoids
Almost identical to cycads
Very structurally similar to cycads
Unique characteristics
Cones
Both microsporophylls and megasporophylls
Differentiation of stomatal complexes
Division Ginkgophyta
Maidenhair Tree
Ginkgo biloba
Morphology
Wood
Lacks vessels/axial parenchyma
Similar wood to conifers
Leaves
Dichotomously branched veins
Broad
Brilliant yellow in fall
Stout trunk
Many branches
Reproduction
Dioecious and gymnospermous
No cones
Ovules in pairs
At stalk ends
Three-layered seed coat
Pollen in catkin-like organ
Two microsporangia each
Division Gnetophyta
Three groups
Ephedra
About 40 species
Reduced, scale-like leaves
Native areas
Desert regions
Northern Mexico
Southwestern U.S.
Dry mountains
South America
Tough shrubs and bushes
Welwitschia mirabilis
Only species in genus
Only two leaves
Grow perennially
Stem from basal meristem
Become increasingly longer
Native areas
Deserts of South Africa
Short, wide stem
Gnetum
30 species
Vines or small shrubs
Broad leaves
Native areas
Tropical Africa
The Amazon Basin
Southeast Asia
Unique characteristics
Wood
Contains vessel elements
Pollen cones
Contain small bracts
Compound
Seed cones
Compound
Extra tissue layers
Surround ovules
