Post on 13-Dec-2015
History of Gymnosperms280 millions years ago, Earth’s
climate changed.
Long periods of drought and freezing weather caused spore-producing plants to become extinct, but some adapted
and survived!
THE GYMNOSPERMS!
What are GYMNOSPERMS?
1. Vascular plants that produce seeds on cones
2. Seeds are not protected by fruit
3. Do not produce flowers
NAKED SEEDS!
Gymnosperms produce spores!Male cones
Microspores
Male Gametophyte
Pollen (Sperm)
Female cones
Megaspores
Female Gametophyte
Egg Cell
Sperm and egg eventually meet!
NO water necessary!
Gametophyte Development
Male Gametophyte - develops in pollen grains
Female Gametophyte - develops in ovule
What happens next?
•After fertilization, the zygote develops into an embryo.
•Gymnosperm embryos have many Cotyledons
•Cotyledons are food-storage organs that become the plant’s first leaves
Gymnosperm Advantages!
1. Seeds have embryo w/food supply
2. Seeds are protected from harsh conditions by tough seed coat.
3. Seeds are adapted for dispersal so young plant does not have to compete with parent.
4. Fertilization does not require water
From cereal and fruit to cotton and linen…
ANGIOSPERMS!
-Most well-known plants on Earth-Have seeds, roots, leaves, stems, and
FLOWERS and FRUIT!
ANGIOSPERM ADAPTATIONS!1) Roots and stems store food
2) Leaves of different shapes and sizes to respond to amount of sunlight and
moisture available.
Life Span of Angiosperms
ANNUAL - live for one year or less
BIENNIAL - live for 2 years
PERENNIAL - live several years, flowering once each year