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ON THE COVER | NEWS & VIEWS January 10, 2008
The Shady Lives of Fernsby Don Garlick
A fern’s life cycle is more complex. It alternates generations between a large diploid “sporophyte” plant that produces haploid spores and a small haploid “gametophyte” plant, grown from a spore, that produces sperm and egg gametes. A sperm swims through water to fertilize an egg which then grows into the familiar fern. The gametophyte is inconspicuous because it is smaller than a finger nail, is photosynthetic green and has a relatively short life (measured in months).
Mosses alternate generations after the fashion of ferns, but their gametophytes are larger than their sporophytes, and mosses are not vascular (they lack plumbing). Above: “Five Finger Fern,” Adiantum pedatum, at Bull Creek.
Don Garlick is a geology professor retired from HSU. He invites any questions relating to North Coast science, and if he cannot answer it he will find an expert who can. E-mail dorsgarlick@yahoo.com.
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A human female is diploid, having paired maternal and paternal chromosomes. She is born with over a million haploid eggs with unpaired chromosomes. Each egg has the potential of being fertilized by a haploid sperm. 
Ferns are shade-tolerant and thus common in our forests. They are also quick to recolonize burnt forests. Asteroidal impacts and their fires that terminated the Triassic and Cretaceous Periods allowed ferns to flourish for several years, as documented by spores preserved in sediments.