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Key to Species

I.--Leaves entire, margins inflexed, apex obtuse, P. sexangulare.

Apex rough-awned.

Awn coloured brown or red, short. Leaves spreading when moist, somewhat recurved . . P. juniperinum.

Awn whitish, transparent, long ..... P. piliferum.

II.--Leaves serrate.

Marginal cells of lamellae not enlarged in section, higher than broad.

Spore-case egg-shaped, obscurely angled.

Lid beaked . . . . . P. gracile.

Spore-case oblong, 4- to 6- angled.

Lid acutely conic, P. formosum.

Marginal cells of lamellae enlarged, broader than high, 2 to 1 . . . . . P. Ohiense. Marginal cells of lamellae semilunar, with two prominent horns at corners, P. commune.

Slender Hairy-cap, Polytrichum gracile, Dicks.

Habit and habitat.--The slender Polytrichum is not common. It may be found densely tufted--on the ground in woods, or on rocks.

Name.--The specific name gracile is from the Latin gracilis, slender.

Plant (gametophyte).--Light green, erect, 1 to 4 inches high, simple above, divided at the base and covered with soft matted hairs.

Leaves.--Spreading or erect when dry, broadly lance-shaped; apex sharply taper-pointed; base sheathing; vein broad; margins serrate; lamelloe 30 to 40, not covering all of the leaf blade, 4 to 6 cells deep, the terminal cell elliptic in section.

Leaves at the base of the pedicel (perichoetial leaves).--Sheathing, 1/2 an inch long.

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

Veil (calyptra).--Orange, not quite covering the spore-case.

Spore-case.-- Erect or horizontal, broadly egg-shaped; indistinctly six-angled, mouth small; apophysis obscure.

Pedicel (seta).--Slender, orange, 1 1/2 to 2 inches long.

Lid (operculum).--Conic, beaked.

Teeth (peristome).--With 64 teeth often confluent and unequal.

Spores.--Mature in summer.

Distribution.-- From the mountains of Virginia to Newfound-land and west to the Rocky Mountains. Also in Europe, Asia and the Pacific Isles.

Ohio Hairy-cap, Polytrichum Ohiense, Ren. and Card.

Habit and habitat.--Found on the ground growing loosely in patches. Distinguished from P. formosum* by the form of the spore-case, which is more or less narrowed toward the base and has an indistinct apophysis, but chiefly distinguished by the form of the marginal cells of the lamellae, a character which separates it from all our other species of Polytrichum.

Name.--The specific name Ohiense refers to the fact that the type specimen came from Ohio.

Plant (gametophyte).--Erect, simple or divided, 1 1/2 to 3 inches high, woolly below.

Leaves.--Spreading when moist, erect and slightly twisted when dry; apex narrowly taper-pointed, the awn spiny; base white, sheathing; margin serrate; lamelloe 30 to 40; cells 5 to 7 deep, the marginal cell much larger, broader than high, stirrup-shaped in section.

Leaves at the base of the pedicel (perichoetial leaves).--Resembling the stem-leaves, longer and with a longer transparent base.

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

Veil (calyptra).--Pale, small, ragged, not concealing the spore-case.

Spore-case.--Erect, finally horizontal, with 4 to 6 acute angles, the base tapering into an indistinct apophysis.

Pedicel (seta).-- Red below, paler above, 2 to 4 inches long.

Lid (operculum).--Conic and taper-pointed, bordered with orange.

Teeth (peristome).--Sixty-four.

Spores.--Rust colour, ripe in summer.

Distribution.--North Carolina to Prince Edward's Island, and west to Minnesota and British Columbia. Also in Norway and Sweden.

The Awned Hairy-cap, Polytrichum piliferum, Schreb.

Habit and habitat.--Found in sandy fields, on rocks or on old roofs, conspicuous on account of the white hair-like tips and the bluish-white bloom of the leaves; the plants in clusters but not matted together. The male flower-clusters surrounded with red bracts. The specific name piliferum is compounded of two Greek words,hair, and to bear, referring to the numerous white hairs of the leaves.

Plants (gametophyte).--Short, 1 to 1 1/2 inches high, simple from subterranean creeping shoots, wiry and naked below, densely leafy above.

Leaves.-- The upper long lance-shaped, the lower oval, appressed to the stem when dry, spreading when moist; apex smooth on the back, prolonged into a rough, hair-like awn; margin entire, inflexed upon the upper surface of the leaf-blade; vein red, becoming suddenly transparent at the apex; lamelloe about 30, 4 to 7 cells deep, the upper cell pointed in section.

Leaves at the base of the seta (perichoetial leaves).--Narrowly tongue-shaped, erect, concave, without lamellae; base sheathing, transparent, shorter than the awn.

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

Veil (calyptra).--Mitrate, covering the spore-case.

Spore-case.-- Erect, finally horizontal, egg-shaped, 4-angled. Apophysis distinct, constricted above where it passes into the spore-case.

Pedicel (seta).--Erect, 1 to 1 1/2 inches long.

Lid (operculum).--With a short stout beak, red or orange.

Teeth (peristome).--Symmetrical, sixty-four in number.

Spores.--Smooth, ripe in summer.

Distribution.-- America, Europe and Asia.

Juniper Hairy-cap, Polytrichum juniperinum, Willd.--See Plate XXI.

Habit and habitat.--Common by damp sandy roadsides, or in peat-bogs. This is one of the Hairy-caps which in dry air turns its leaves up against the sun in order to protect the delicate lamellae from his rays. It as well as P. piliferum, is conspicuous for its bluish-white bloom, but differs from P. piliferum in that the leaves are tipped with a short red awn instead of with one long, white, and hair-like.