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 windpollinated.
• 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
3 distinct groups:
Gnetum
Welwitschia
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
Pollen
Tube
(carpel)
Embryo
Ovary
Ovules