gymnosperms (naked seeds)
DESCRIPTION
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: - PowerPoint PPT PresentationTRANSCRIPT
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
Gnetophyta3 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)
Microsporangium
(anther)
Megasporangium
(carpel)
Pollen
Ovules
Ovary
Embryo
Fruit
Endosperm (3n)
GAMETOPHYTE (n)
SPOROPHYTE (2n)Seed
Coat (from mom)
Mature Sporophyte
Embryo
Endo.
Pollen Tube