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Fork-mosses

Genus DICRANUM, Hedw.

The species of this genus are universally distributed, and include some of our most easily recognised mosses. They usually grow in dense tufts or cushions on the ground or on old decaying logs or even on rocks. About two hundred and thirty-four species are known in all; about sixty-three are found in North America, six of these within the limits of New York City. Their showy dark-green or glossy yellow-green cushions are often conspicuous in damp shady places and consist of numerous more or less erect and forking stems, often crowded together and covered with a felt of reddish hairs at least below, with lance-shaped often curved leaves above that spread all about the stem or turn to one side.

The leaves have a slender apex with a vein usually broad and extending into the apex. The character of the vein and the cell-structure are relied upon for perfect classification of the species. The cells vary from short to linear oblong in the upper part of the leaf, to long and narrow in the lower part; four-sided, inflated, orange or brown, in the angles of the base. The leaves at the base of the pedicel are sheathing and abruptly pointed. The spore-cases are erect or turned to one side, the base, which is often swollen so as to be unsymmetrical, tapers to an erect pedicel, long and smooth. An annulus is generally present. The lid is conical with a long beak. The peristome is single, of sixteen teeth, two-cleft to the middle and red-brown at the base.

The name of the genus is derived from a Greek word. a flesh-hook or fork, from a supposed resemblance of its teeth to that instrument. The American Indians call Fork-mosses "Women's heads," "because when you trample them under foot they spring right up again."

Although at first glance the Dicranums appear to have their spore-cases on the sides of the plants, they truly belong to the group of mosses which bears them on the summits of the stems (acrocarpi) and not to the group which bears them on the sides of the stems (pleurocarpi), for a closer examination shows that a side stem grows on after the spore-case has begun to develop, leaving the spore-case and pedicel behind on the apex of the main stem. The felt of hairs on the stems serves as a sponge through which water may creep to the upper parts of the plants.

"How glorious are the summer woods,

Where the bright Broom Fork-moss grows,

With their gush of love-born melody,

And their world of verdant boughs."

Whip Fork-Moss, Dicranum flagellare, Hedw.--See Plate XIV.

Habit and habitat.--Growing in bright green, dense tufts producing fragile, small-leaved branches (flagelloe) in the axils of the upper leaves. Common on decayed trunks in deep woods.

Name.--The specific name flagellum, the Latin for "whip," refers to the young branches, which are so small as to be easily overlooked. They fall away as the plant dries.

Plant (gametophyte).--Repeatedly branching; stems 1 to 2 inches high; covered with a thick felt of hairs.

Leaves.--Forming little clusters on the summits of the stems; lance-shaped, convolute; apex toothed, turned back from the stem, the upper twisted when dry; margin below entire, incurved; vein broad, compressed, extending to the apex; cells inflated at the basal angles, yellow-brown, four-sided. The leaves of the "whips" have no vein.

Leaves at the base of the pedicel (perichoetial leaves).--Rolled about the pedicel.

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

Veil (calyptra).--Split on one side.

Spore-case.--Erect symmetrical, long, cylindrical, grouped lengthwise when dry.

Pedicel (seta).--Pale, twisted to the left when dry.

Lid (operculum).--Conical, with long oblique beak.

Annulus.--Narrow.

Teeth (peristome).--Sixteen, narrow, cleft nearly to the base.

Spores.--Mature in autumn.

Distribution.--North America, Asia, Africa; rare in Great Britain.

The Broom-moss, Dicranum scoparium, Hedw.--See Plate XIII.

Habit and habitat.--The Broom-moss, Dicranum scoparium, is a conspicuous species. It commonly grows in the woods forming large and symmetrical cushions on the ground, although it may extend in large patches over decaying stumps and logs or on the ground where there is a rich vegetable mould. The long beaked spore-cases, tilted on one side, commonly point one way, and the leaves also are all tuned to one side pointing in the same direction as the beaks. Children fancy they resemble duck heads and see in them flocks travelling toward the water. Some call them soldiers and sing "The troops of Dicranum are tilting their lances."

Name.--The specific name scoparium, the Latin for "broom," is suggested by the resemblance of the plants to small counter-brooms.

Plant (gametophyte).--Large; stems 2 to 5 inches high in loose yellow, rarely green, tufts, covered with rootlets to the newest growth, forking once or twice.