1. Land Plants – The Gymnosperms

2. Gymnosperms: “Naked Seeds”
Seed bearing plants
Seeds are not enclosed by a ripened ovary (fruit)
Bear separate male and female cones
Have vascular tissue
Have roots that extend over a wide surface area
species
Are divided into four groups
Cycadophyta
Ginkgophyta
Gnetophyta
Coniferophyta

3. The Cycads Resemble palm trees but are cone bearing
Have fleshy stems and leathery, featherlike leaves
Can grow to 19 m in height
Have motile sperm that swim to the egg in the ovule

4. The Ginkgos Primitive tree first found in the highlands of China
Dioecious : has separate male and female trees (the “fruits” of the female tree smell very foul!)
Leaves are fan shaped and thick with leathery veins
Have motile sperm that swim to the egg in the ovule

5. The Gnetophytes
Can be found as shrubs, vines or massive squat stems (see examples of Welwitschia to left)
Have sperm with no flagella that travel to the egg via a pollen tube which grows through the ovule tissue

6. The Conifers
Many conifers are evergreen and retain their leaves in the winter
Can grow very large and to old ages (Giant Sequoia trees are known to live for thousands of years)
Are adapted to severe climates and conserving water with
leaves that are covered with waxy cuticles and are needle shaped
pores (stomata) are sunken below the leaf surface to decrease rate of evaporation
Have sperm with no flagella that travel to the egg via a pollen tube which grows through the ovule tissue

7. Adaptations for Life on Land
Gametophytes are more reduced in size, often staying within the parent sporophyte
Swimming sperm are replaced with pollen (in conifers and gnetophytes) which is dispersed by wind and insects
Seed formation. Embryos develop from zygote in a protected seed that also supplies food and a method of dispersal

8. Seedling begins to grow
Pine Life Cycle
Seedling begins to grow
Male cone
GERMINATION
Pollen sac
Mature sporophyte
Seed
Zygote: forms in the middle of the female gametophyte which serves as its food. A seed coat is also formed around it with a wing to aid in dispersal
Female cone
Ovule
MEIOSIS
DIPLOID (2N)
Megaspore: Produces archegonium with egg
HAPLOID (N)
FERTILIZATION
Microspores: Pollen Grains
POLLINATION
Pollen lands on the female gametophyte and forms a pollen tube to the archegonia and the egg through which the sperm will travel

9. Ecological Roles of Gymnosperms
Help to maintain balanced levels of gasses in the atmosphere
Act as food and shelter for other organisms
Control flooding and erosion by absorbing rainwater with roots and holding soil in place

10. Economical Role of Gymnosperms
Provides 85% of all wood used in building and furniture
Pulp and paper industry
Used to produce varnish, turpentine, disinfectant, paint, some soaps and taxol
Some types are edible
Used in the production of some perfumes