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Chapter 8 Section 4 Gymnosperms.

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1 Chapter 8 Section 4 Gymnosperms

2 Gymnosperms A seed plant that produces naked seeds
Not enclosed by a protective fruit Many gymnosperms have needle-like or scale-like leaves, and deep-growing root systems Oldest type of seed plant

3 Grow mainly in tropical and subtropical areas
Cycads Grow mainly in tropical and subtropical areas Look like palm trees with cones Cone can grow as large as a football

4 Conifers Cone-bearing Largest and most diverse group of gymnosperms
Most keep their needles year round

5 Ginkgoes Only one species exists today, Ginkgo biloba
Chinese and Japanese cared for it in their gardens Planted along city streets because they can tolerate air pollution

6 Live in hot deserts and in tropical rain forests
Gnetophytes Live in hot deserts and in tropical rain forests Trees, shrubs, and vines

7 Reproduction of Gymnosperms
Cones: reproductive structures in most gymnosperms Males cones Produce tiny grains of pollen (the male gametophyte) Later become sperm cells Female Cones Ovule: female gametophyte Contains egg cell Develops into seed

8 Gymnosperm Reproduction
Pollen falls from male cone onto female cone Sperm cell and egg cell join together in an ovule on the female cone After fertilization, the seed develops on the scale of the female cone

9 Pollination Transfer of pollen from male reproductive structure to female reproductive structure Wind often carries the pollen

10 Fertilization Once pollination occurs, the ovule closes and seals in the pollen Sperm cell and egg cell are inside each ovule The egg is fertilized and develops into the embryo

11 Seed Development Female cones remain on tree while seeds mature
Can take up to 2 years Male cones usually fall off tree after they shed their pollen

12 Seed Dispersal When seeds mature, scales open
Wind shakes seed out of cone and carries them away Only a few seeds will land in suitable place

13 Page 275


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