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Polytrichum formosum Hedw. | |
Family POLYTRICHACEAE Common names HAIRCAP
MOSS Microhabitat This species grows on soil or sometimes rock in very wet, shaded areas. Our specimen was growing on soil in a deeply shaded, boggy area alongside Tatlow Trail in Stanley Park. Distribution Polytrichum formosum can be found in temperate zones of the Northern Hemisphere, including Greenland, Europe, North Africa, central Asia, Nepal, Japan, and across North America. In British Columbia it is distributed from sea level to over 2000 m. |
Probably a single genetic individual 
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Morphology This acrocarpous moss has upright gametophores ranging from about 4 to 10 cm long. Its narrow leaves are 5 to 12 mm long with serrate margins and a pointed, reddish tip, and they project from the main vertical stem in a spiral arrangement. The leaves also have lamellae on their upper surface; this character is diagnostic of the order Polytrichales. In this species, the lamellae are 3 to 5 cells high with a somewhat conical uppermost cell. The sporophytes of this dioicous moss are 4-8 cm long when mature. The seta is not twisted and the capsule can be erect or horizontal. The nematodontous peristome teeth curve around an epiphragm, and spores are dispersed as if from a salt shaker from between the teeth. This peristome type is characteristic of the Polytrichales. The calyptra is hairy, which is why Polytrichum species are often called haircap mosses. The mature capsule has four distinct longitudinal ridges. Key identifying features The genus Polytrichum is quite distinctive, with large gametophores that resemble tiny conifer trees. This gross morphology is similar to the genera Atrichum and Pogonatum, which are also in this family, but Atrichum has no hair on its calyptra, and Pogonatum has a terete capsule. To confidently identify this moss as Polytrichum formosum, you’ll need a microscope. Polytrichum commune has notches in the top row of cells of its lamellae. Polytrichum longisetum and P. formosum are very similar, except that P. formosum has smaller leaf cells (10-12 um) than P. longisetum (15-30 um). Also, the leaf margin only extends 3-5 cells beyond the outermost lamella in P. formosum, while it extends 7-9 cells in P. longisetum. Polytrichum juniperinum also looks macroscopically similar, but its leaf margins are entire, not serrate. Interesting notes The genus name means “many hairs” and refers to the hairy calyptra. The specific epithet formosum comes from the Latin word for beautiful or handsome. This name is not to be confused with the epithets formosana or formosanum, however, which mean “from Taiwan”. The old Portugese name for the island of Taiwan was Formosa, which comes from the same Latin root. Mosses in the family Polytrichaceae have specialized vertical rows of cells called lamellae on their upper leaf surfaces. These lamellae are analogous to the palisade parenchyma layer of angiosperm leaves, in that they provide depth within the leaf to protect chloroplasts and take advantage of higher light levels for photosynthesis. Mosses in this family have the highest photosynthetic potential, but this species happens to prefer deeper shade than other species in the family. Selected References Crum, H. A., and Anderson, L. E. 1981. Mosses of Eastern North America. Columbia University Press, New York.Grout, A.J. 1936. Moss Flora of North America, North of Mexico, Vol. I, Part 1. Published by the author, Newfane, Vermont. Lawton,
E. 1971. Moss flora of the Pacific Northwest. The Hattori Botanical
Laboratory, Ninchinan, Miyazaki, Japan. By Gillian Gile Home >> Species List >> Polytrichum formosum © 2006 Department of Botany, University of British Columbia |
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