Plant Diversity

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Reproduction Free From Water

Adaptations that allow seed plants to reproduce without water include:

flowers or cones

the transfer of sperm by pollination

the protection of embryos in seeds

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Reproduction Free From Water

Cones and Flowers:

Gametophytes grow within sporophytes called cones, which are the seed-bearing structures of gymnosperms, and flowers, which are the seed-bearing structures of angiosperms.

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The male gametophyte is contained in a tiny structure called a pollen grain.

Sperm do not need water to fertilize eggs; instead the pollen grain is carried to the female reproductive structure by wind, insects, or small animals.

This transfer of pollen is called pollination.

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Seeds

A seed is an embryo of a plant that is encased in a protective covering and surrounded by a food supply.

An embryo is an organism in its early stage of development.

The seed coat surrounds and protects the embryo and keeps contents of the seed from drying out.

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Internal Structures of a Seed

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Gymnosperms—Cone Bearers

The four groups of gymnosperms are:

gnetophytes

cycads

ginkgoes

conifers

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Gymnosperms—Cone Bearers

Cycads

Cycads are palmlike plants that reproduce with large cones.

They first appeared during the Triassic, 225 million years ago.

They grow naturally in tropical and subtropical places.

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Gymnosperms—Cone Bearers

Ginkgoes

Today the phylum Ginkgophyta contains only one species, Ginkgo biloba. The living Ginkgo species looks like its fossil ancestors.

Ginkgo trees are planted in U.S. cities because of their resistance to air pollution.

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Gymnosperms—Cone Bearers

Conifers

Conifers are the most common gymnosperms, with more than 500 known species.

Conifers include pines, spruces, firs, cedars, sequoias, redwoods, junipers, and yews.

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Conifers -The Cedars

Female Cones

Male Cones

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Conifers – Cone Bearers