Gymnosperms (naked seeds) • Diverged 150 mya, when Earth became warmer and drier and the swamp forests declined. – no swimming for the sperm. • Members of this group do not produce flowers and all are wind-pollinated. • There are 4 distinct divisions: • Coniferophyta(cone-bearing trees and shrubs) • Ginkgophyta(flat fan-shaped leaves) • Cycadophyta(palm-like appearance) • Gnetophyta[3 distinct and unusual groups: gnetums, Welwitschia, and Mormon tea (Ephedra)]
Coniferophyta Includes pines and other cone-bearing trees and shrubs.
Ginkgophyta • Flat fan-shaped leaves • Native to Asia • Only one extant species, Gingko biloba…. It’s a living fossil! • It’s also an endangered species.
Cycadophyta • Palm-like appearance • Found primarily in tropical regions around the world. • Some species are very endangered
Gnetophyta Welwitschia 3 distinct groups: Gnetum Ephedra
Pine Life Cycle • All gymnosperms are wind-pollinated trees or shrubs, but insect pollination can happen too. • Most are unisexual, with M and F reproductive structures on different parts of the same plant. • They are heterosporous: male microspores develop into pollen, and female megaspores develop into the female gametophyte. • The female gametophyte is not free-living, but retained within the megasporangium where it is nourished by the sporophyte parent plant.
Angiosperms • Phylum (division)Anthophyta Nope. • The carpel, a vessel in which the ovules are enclosed, is unique to angiosperms. • After fertilization the ovule develops into a seed (like gymnosperms), while the carpel matures into a fruit (unique to angiosperms)
Angiosperm flowers • Flowers are composed of both male and female reproductive structures • Many flowers are self-fertile, but cross-fertilization is important in maintaining genetic diversity. • Pollinators, such as birds, insects, and mammals help transfer pollen from flower to flower. (~85% of it, actually)
2) Alternation of generations (Angiosperms) GAMETOPHYTE (n) SPOROPHYTE (2n) Seed Mature Sporophyte Fruit Coat (from mom) Embryo Endosperm (3n) Endo. Microsporangium (anther) Pollen Megasporangium (carpel) Pollen Tube Embryo Ovary Ovules