1. Very small gametophytes are nourished and protected inside paternal sporophyte

2. Pollen grains which provide protection and dispersal for male gametophyte

3. The seed which protects and disperses the new sporophyte embryo.

Advantages of the Seed

1. Multicellular embryo gets a "head start" at the germination stage

2. Stored food for embryo also allows head start, and allows extended dormancy

3. Because it is multicellular/more complex, it is more resistant to harsh conditions, seed coat can govern dormancy

4. Larger, increased capacity to develop dispersal adaptations. 

Advantages of Pollen

1. Fertilization does not require water for sperm to swim through!

2. Pollen disperses well, allowing fertilization over long distances

Disadvantages of the Seed

more energetically costly to produce, trades

quantity for quality.

Ginkophyta

1. Ancestral, exist today only as planted trees

2. Dioecious

3. Flagellated Sperm?

Cycadophyta

1. Resemble palms

2. ~130 species today

3. Many are insect pollinated

Three Genera: Welwitschia, Gnetes, and Ephedra

• Mostly dioecious
• Only Gymnosperms with Vessel Elements in Xylem
• Pollinated by wind and insects
• Double fertilization?
• Medicinals
• Most likely sister clade to coniferophyta rather than angiosperms

Ephedra

in phylum gnetophyta

• used as decongestant, and when mixed with caffeine is powerful metabolic stimulant
• contains ephedrine and related alkaloids

in phyla gnetophyta

• 30-40 sp.
• found in tropics
• possible double fertilization
• female gametophyte nourishes embryo
• netted veination
• used for diabetes, arthritis, aids

in phyla Gnetophyta

• adapted to dry conditions
• extensive taproot
• two leaves
• can live over 1500 years
• lives in western skeleton coast of African desert

Coniferophyta

• often locally dominant species
• include some of the largest, oldest organisms on earth
• wind dispersed pollen
• multi year life cycle
• evergreens with pine needles are adapted to conserve water, deal with short growing season

Conifer Life Cycle