Gymnosperms

Seed Plant 5 characteristics

1. Seed to protect Embryo

2. Xylem & Phloem

3. Sporophyte Dominant

4. All are heterosporous

5. (Most) Megaphylls and true roots

Gymnosperm "naked seed"

Mostly Evergreen

No fruit - reproduce with cones

1. Phylum Coniferophyta "Cone Bearing"

- Conifers with needle megaphylls

- resin ducts : slows fungal and insect infestations

- Thick bark

Cones

heterosporous , spore producing

Staminate cones

Male, small

- produced in spring

1. Microsporangia

sporangia protected by microphylls

Microgametophytes

spore mother cells > meiosis > microspores > Microgamet.

- Wind dispersed pollen grains

- four cells and 2 air sacs

Ovulate Cones

Female Cones, house seeds

Long on upper branches

1. Megasporangium

mega sporophylls & Ovule at base

* each ovule has nucellus

Integument

protective covering

Inside Nucellus

meiosis > megaspore > megagametophyte

2. Megagametophyte

Egg cell

Pollination

1. Staminate cones release pollen as scales on ovulate cones open

2. Pollen drifts up & gets caught in sticky fluid near opening (micropyle)

3. Ovulate cones close

4. Over 15 months, tube cell digs "pollen tube" to egg

5. Sperm move through tube (fertilization)

Fertilization

sperm + egg -> zygote

Seed

1. house embryo

2. food

3. protection

4. wing for dispersal

Coniferophyta Examples and Uses

Examples: Redwoods , Pine trees

Uses: Lumber, paper, pine tar, rosin

2. Phylum Cycadophyta

- tropical (140 spc)

- looks like palm with cones

3. Phylum Gnetophyta

- (70 spc)

- low to grownd, broad leathery leaves / some more shrub or vine-like

4. Phylum Ginkophyta (1 spc)

- Ginko biloba / Maiden hair tree

- Deciduous and Dioecious

- resistant to air pollution

- females produce foul smelling fruit