Google Earth Community: Ferns

Ferns are beginning another season of growth in temperate regions of the Northern Hemisphere. About 20,000 species of ferns are recognized worldwide.

The following photographs of ferns were taken at Poets' Walk Park on May 5, 2008.

Christmas Fern (Polystichum acrostichoides)

Common Polypody (Polypodium virginianum)

Lady Fern (Athyrium filix-femina)

New York Fern (Thelypteris noveboracensis)

Sensitive Fern (Onoclea sensibilis)

Ferns undergo an alternation of generations in their life cycle. The familiar large generation is the sporophyte. It produces spores, which germinate into the next generation, which is a smaller, generally heart-shaped, gametophyte. The gametophytes usually live in moist places where they produce sperms and eggs, which can swim through films of water and unite to form a zygote, which then grows into a sporophyte to complete the cycle of generations. In addition, most ferns can reproduce through rhizome spreading, and a few, such as the Bulblet Fern, produce reproductive bulblets on their leaves. The leaves of the Walking Fern have long pointed tips that can produce new plants when they touch the ground. Ferns can be germinated from spores in a moist protective container for horticultural purposes.

Alternation of generations in ferns. Image from Australian National Botanic Gardens

Sori of Polypodium virginianum are clusters of spore capsules. Each capsule contains 64 spores. The shapes of sori are useful in the identification of ferns.

General Information
Wikipedia: Fern
A classification of the ferns and their allies

Life Cycle
Ferns (life cycle)
The Fern Life Cycle
Wikipedia: Sorus
Connecticut Botanical Society: Bulblet Fern

Societies
The American Fern Society
Los Angeles International Fern Society
The San Diego Fern Society
The Hardy Fern Foundation

Publications
The San Diego Fern Society: Fern Books
The Hardy Fern Foundation: Fern Books
Bibliography of Pteridological Works

Fern Gardens and Gardening
Bartholomew's Cobble
Virginia Cooperative Extension: Planting a Native Fern Garden
Australian National Botanic Gardens

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