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The Boat-hook Mosses

HYPNUM: Sub-genus HARPIDIUM, Sulliv.

The species of the Sub-genus Harpidium are found usually in marshes. They have stems divided irregularly into long ascending rootless 'branches sometimes plume-like with short branchlets which are all more or less curved at the apex like a boat-hook.

The leaves are firm and membranous with the apex prolonged into a slender point and turned to one side as a scytheblade; a single vein extends to above the middle or to the apex ; the cells are narrow, enlarged and inflated at the basal angles.

The name Harpidium, the Latin for "hook," describes the hooked leaves, the important character of the sub-genus.

The spore-cases are borne on long smooth pedicels, they are oblong-cylindrical, often arched, with short and conical lids. The teeth are as in the genus Hypnum.

There are numerous species. In the "Kryptogamen Flora," of 1898, K. Gustav von Limpricht, a prominent bryologist, devotes about seven pages to a most intricate classification of the sub-genus Harpidium.

The Hooked Boat-hook Mosses, Hypnum (Harpidium) uncinatum, Hedw.--See Colour Plate III.

Habit and habitat.--In pale yellow-green tufts, erect or drooping, on stones bordering streams, or on shaded ground, rarely on decayed wood, common and variable in mountain regions.

Name.--The specific name, Latin uncinatum, hooked, refers to the character of the leaves.

Leaves.--Long, lance-shaped, grooved lengthwise, the taper-point spreading, scythe-shaped or hooked; apex minutely serrate; vein thin; cells narrow, more enlarged at the base, broader and rectangular at the angles, which are slightly hollow.

Leaves at the base of the pedicel (perichaetial leaves).--Very long, the outer recurved from the middle, the inner soft, long, with a slender thread-like point; apex sharply serrate; vein present.

Habit of flowering.--Male and female flowers on the same plant (monoicous).

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

Spore-case.--Nodding, cylindrical, incurved, constricted under the mouth when dry, brown-orange, darker when old.

Pedicel (seta).--Variable in length, smooth.

Lid (operculum).--Orange, highly convex, conical, acute.

Teeth.--Orange at the base, yellowish above; segments of the inner membrane slightly cleft; cilia two, as long as the outer teeth.

Annulus.--Broad, of three rows of cells.

Spores.--Mature in summer and autumn.

Distribution.--Universal.