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The Torn-veil Mosses

Genus RACOMITRIUM, Brid.

The species of the Genus Racomitrium are usually of large size, with stems branching in pairs, the branches simple and all reaching the same height, or unequal, in lateral clusters. They are widely and loosely tufted on rocks in mountainous regions. Many of the species resemble the Hypnum mosses on account of their long prostrate stems, their numerous short branches, and their apparently lateral spore-cases.

The name is from the Greek ?, a shred, and ?, a veil, referring to the torn base of the veil.

The leaves are not tufted at the top of the stems but are close, nearly equal, long, lance-shaped, concave and channelled, with an apex blunt or ending in a fine point or hair; the margin is recurved; the cells are usually obscure, rounded or four-sided in the upper part, and long and narrow in the lower part.

The spore-cases are oblong cylindrical, narrowed at the orifice and usually erect on erect pedicels. The lids are small and more or less beaked and the peristome consists of a single row of sixteen long teeth cleft two or three times to below the middle, or divided into two thread-like, knotty, nearly equal segments, erect when dry, rarely spreading. The annulus is compound, rolling back when the lid falls.

Eighty-one species are known at present, twenty in North America. They are mostly distinguished from the species of the genus Grimmia by the peculiar narrow and wavy cell-structure of the leaf-base in conjunction with their habit of growth.

The Woolly Torn-veil Moss, Racomitrium lanuginosum, Brid.

Habit and habitat.--Common on the tops of walls and on rocks in mountainous regions. The thick grayish-white tufts extending in wide patches.

Name.--The specific name lanuginosum, woolly, was applied by Bridel to describe the white appearance due to the transparent tips of the leaves.

Plant (gametophyte).--Long and slender, stems 1 to 12 inches long, prostrate, branches in pairs, the side branches numerous.

Leaves.--Close, long-spreading, erect or recurved narrowly lance-shaped, bent to one side toward the apex; apex tapering to a white transparent hair-point often longer than the leaf-blade; vein narrow; margin from the middle upward a pellucid membrane bearing tiny protuberances, and bordered with hair-like teeth, wavy when dry; cells, those of the margin very small, dot-like; those of the leaf-blade narrow.

Habit of flowering.--Male and female flowers on separate plants (dioicous).

Veil.--Resembling a bishop's mitre, long-beaked, rough at the apex only.

Spore-cases.--Oblong, egg-shaped, pale-brown, finally darker.

Pedicel.--Short, 1/5 to 1/2 of an inch long on a lateral branchlet.

Lid (operculum).--Tapering from a conical base.

Teeth (peristome).--Long, cleft into two forks; orange-red.

Annulus.--Broad.

Spores.--Mature in summer.

Distribution.--Universal.