Saturday, August 8, 2009

Hawaii - Dicranopteris

This will be the first in a many-post series about various genera of ferns out here on Hawaii. First up is Dicranopteris, one of the most ubiquitous ferns you'll find at low, moist elevations. As you can see from the two photos below, it will drape itself across large swaths of vegetation, absolutely coating them.

Dicranopteris is really beautiful up close, especially when it's young. Its fiddleheads are purplish, and often sport golden or orangeish hairs or scales:

It has a unique growth pattern, unlike most other ferns. It initially sends up one unbranched frond, with fiddlehead, that unfurls and continues growing upward. Eventually, the upward movement stops and the fiddlehead/bud goes dormant. Just below it, two additional buds emerge and strike out sideways, almost at right angles from the original bud. These grow for awhile until they, too, eventually stop, and the process happens over again. This leads to the draping effect, as the fern basically continuously grows outward. (This description is based on the one in Daniel Palmer's Hawai'i's Ferns and Fern Allies book, published in 2003 by University of Hawaii-Honolulu. It's a great book - get a copy if you're visiting Hawaii or want more information on its ferns.) Another effect of this growth form is that there always seem to be little fronds unfurling somewhere on a Dicranopteris:

You can see its sori in the bottom right photo. The species shown in all of these photos is the only one on Hawaii, Dicranopteris linearis. Incidentally, this is one of the only ferns out here I can identify to species, because there's only one of them. Most of the ferns in the following posts I can only get to genus without a lot more work with the keys. 

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