1. Evolution of Cycads, Gymnosperms and Ferns

2. Div: Progymnospermophyta
Gymnosperm anatomy - secondary xylem tracheids, circular bordered pits - and fern-like fronds & reproductive dispersal by spores. (no seeds)
Arose in Upper Devonian 350 mya --> Pennsylvanian 290 mya
All extinct
Probably the immediate ancestor of all seed plants.
Archaeopteris

3. Div: Pteridospermophyta “Seed Ferns”
Gymnosperm anatomy and gymnosperm seed type with fern-like fronds. (seeds on fronds)
Arose during Carboniferous Period 345 mya --> Permian 250 mya.
All extinct
Probably the immediate ancestor of the cycads.

4. Div: Pteridospermophyta “Seed Ferns”
Ovules (megasporangium with embryo after fertilization) develop into “seeds” covered with two cells layers from integument or seed coat.
Naked Seed, “Gymnosperm”
Monoecious

5. Div: Cycadophyta “Cycads”
Resemble “palm trees”.
Cycad foliage does not bear ovules or seeds - these are in special seed cones (strobili); pollen (with sperms) produced in pollen cones.
Arose during Permian Period 280 mya --> extant
A dominant form of vegetation during the Jurassic and Triassic Periods --> 135 mya.

6. Div: Cycadophyta “Cycads”
All are dioecious: Micro and Megasporangia (strobili) on separate plants.
Cycas

7. Div: Cycadophyta “Cycads”
Reproductive cycle in cycads wind pollination; pollen droplet
4 - 6 months between
pollination &
fertilization
interval between pollination and fertilization: months.

8. Div: Cycadophyta “Cycads”
Two motile sperms produced by each pollen tube --> archegonial chamber.
Cycads & Ginkgos are
only seed plants with
motile sperm

9. Div: Cycadophyta “Cycads”
No fixed period of dormancy in cycads.

10. Evolution of Seed Plants
Derived Trait

11. Evolution of Seed Plants Gymnosperms
Pollen - Encased male microgametophyte (n) that produces
sperms (n).
(Frees plant from the need for water in the pollination
process.)
prothallus cell(s), tube cell(s), generative cell
---> sperms
Ovule - The female megagametophyte (n) with eggs (n) surrounded
by the old megasporangium (2n) with two layers from the
old sporophyte (2n) that will form the integument (2n).
(Frees plant from the need for water in fertilization.)
Cones - An axis bearing a tight cluster of scales or leaves for
reproduction. Scales either bear microsporangia or
meagasporangia in separate cones. (Pollen & Seed Cones)
Seed - ?

12. Evolution of Seed Plants Gymnosperms
Seed - The matured ovule with an embryo in a resting state.
Integument - (2n) May be fleshy
Female Gametophyte - (n) nuritive; includes nucellus
Embryo - (2n) forms from zygote after fertilization.

13. Evolution of Seed Plants Gymnosperms

14. Div: Ginkgophyta “Ginkgos, Maidenhair Trees, Yin hing (silver apricot)”
Arose during the Permian 250 mya.
Richly branched woody plant with simple leaves.
Ginkgo biloba living fossil

15. Div: Ginkgophyta 1. Large stems; small simple leaves; deciduous.
2. Dioecious (female more shrubby)

16. Div: Ginkgophyta 1. Large stems; small simple leaves; deciduous.
2. Dioecious (female more shrubby)
3. Has bud scales; dimorphism in branches. (long and spur shoots).
4. Stomates on abaxial (bottom) of leaf; two vascular bundles and 2 leaf traces per leaf.

17. Div: Ginkgophyta 1. Large stems; small simple leaves; deciduous.
2. Dioecious (female more shrubby)
3. Has bud scales; dimorphism in branches. (long and spur shoots).
4. Stomates on abaxial (bottom) of leaf; two vascular bundles and 2 leaf traces per leaf.
5. Initiation of cambium after primary growth; growth rings.
6. Cork cambium or phellogen develops in outer cortex --> phellem (cork cells, bark)

18. Div: Ginkgophyta Reproduction: Dioecious
Microsporangia (2n) - strobili
1 yr. --> microsporocyte (2n) > meiosis --> microspores (n) Spring --> pollen (male gametophyte)
Pollination (pollen droplet mucilaginous) -->
Megasporangia - ovules
1 yr. Development of megasporocyte (2n) --> meiosis --> megaspore (n) --> female gametophyte ( with egg - n) as pollen tube grows - after 5 mos.
(Aug-Oct) fertilization - development of seed - 2nd yr.

19. Div: Ginkgophyta Reproduction: Fertilization the 2nd Year
generative cell --> 2 flagellated sperms (just prior to fertilization) --> swim to end of pollen tube
egg from archegonium swells and forces apart neck cells --> exposed to pollen tube and sperm for fertilization.
Micropyle

20. Div: Ginkgophyta Reproduction: Development
seed

21. Div: Ginkgophyta Reproduction: Development
Outer fleshy layer of the integument emits foul order!
However, inner part of the seed is edible!

22. Div: Coniferophyta “Pines”, “Spruces” and “Firs”
Evolved during the Carboniferous Period 325 mya

23. Div: Coniferophyta “Pines, Spruces and Firs”

24. Div: Coniferophyta “Pines, Spruces and Firs”

25. Div: Coniferophyta “Pines”, “Spruces” and “Firs”
Evolved during the Carboniferous Period 325 mya
1. Leaves simple; often needle-like or scale-like.
2. Xylem compact, composed mostly of tracheids (seasonal growth - rings).
3. Pith and cortex restricted - xylem composes most of the stem.

26. Div: Coniferophyta “Pines”, “Spruces” and “Firs”
1. Leaves simple; often needle-like or scale-like.
2. Xylem compact, composed mostly of tracheids (seasonal growth - rings).
3. Pith and cortex restricted - xylem composes most of the stem.

27. Div: Coniferophyta “Pines”, “Spruces” and “Firs”
1. Leaves simple; often needle-like or scale-like.
2. Xylem compact, composed mostly of tracheids (seasonal growth - rings).
3. Pith and cortex restricted - xylem composes most of the stem.
4. Stem may be differentiated into long and spur shoots.

28. Div: Coniferophyta “Pines”, “Spruces” and “Firs”

29. Div: Coniferophyta “Pines”, “Spruces” and “Firs”
1. Leaves simple; often needle-like or scale-like.
2. Xylem compact, composed mostly of tracheids (seasonal growth - rings).
3. Pith and cortex restricted - xylem composes most of the stem.
4. Stem may be differentiated into long and spur shoots.
5. Leaf traces one or few per leaf.
6. Typically evergreen; loose leaves gradually.
7. Protostelic taproot.

30. Div: Coniferophyta “Pines”, “Spruces” and “Firs”

31. Div: Coniferophyta
Seed or Ovulate Cone
Pollen or Staminate Cone

32. Div: Coniferophyta
Pine Pollen

33. Div: Coniferophyta
Ovulate Pine Cones:

34. Div: Coniferophyta
Mature Pine Ovule with Two Archegonia:

35. Div: Coniferophyta
Ovules at Fertilization and with Embryo:

36. Div: Coniferophyta
Pine Seedling:

37. Div: Coniferophyta