Friday, April 9, 2004
Biodiversity Corner Common script lichen
When and where seen: I found the sample in the photo on the bark of a large oak in my back yard. It is on the south-facing side of the tree, conveniently located just about at eye-level. It is quite common — I have some on other oaks and also on some smooth-barked maple saplings. Look for an area of a lighter gray color than the rest of the bark. On oaks, look for smooth patches, then look closely for the "script" markings.
More lichen language: If the fruiting body of a lichen is disk- or cup-shaped, it is called an apothecium, like the red cap on a British Soldier lichen. If it is elongated and perhaps branched, it is called a lirella. The black marks that give the script lichen its name are the fruiting bodies or lirellae.
Distinguishing characteristics: The common script lichen is whitish-gray and very thin. It is a crustose lichen, meaning that it is very closely bonded to the substrate and forms a crust over it. The spore-bearing lirellae look like black lines of variable length up to a quarter-inch long; some are curved; some are forked. If you find some of this lichen on grained bark, like birch, the lirellae will probably be straight, following the line of the grain. Close inspection of the lirellae, with a hand lens, will show that they have raised edges, and taper off to a point at either end — they look like little mouths with black lips.
Biodiversity word for the week: Corticolous means growing on bark. Lichens in the genus, Graphis, are corticolous. There are woodscript lichens in the genus Xylographa, which are not corticolous — they grow on old weathered wood that has lost its bark.
References: Lichens of North America, by Brodo, Sharnoff and Sharnoff.
Submissions for the Biodiversity Corner are encouraged from everyone. Spring things are happening — the hazelnut is in flower at the Conant Land, fireless fireflies are crawling around the tree trunks; there is much to see and write about. Be the first to write up a moss, a spider, a fish. Send to Kay Fairweather at 392 School St, Carlisle MA 01741 or to firstname.lastname@example.org
© 2004 The Carlisle Mosquito