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The Eight-toothed White Mosses

Genus OCTOBLEPHARUM, Hedw.

The Genus Octoblepharum very much resembles the genus Leucobryum, the principal difference being that the genus Octoblepharum has but eight teeth instead of sixteen. This characteristic gives it its name from the Greek OKTW, eight, and eyelash.

There are fifteen species in all, eight of them in North America.

The Eight-toothed White Moss, Octoblepharum albidum, Hedw.

Habit and habitat.--In small white cushions on bark and on shady rocks.

Name.--The specific name albidum, white, refers to the colour of the leaves.

Plant (gametophyte).--Spongy, soft when wet, brittle and white when dry.

Leaves.--Close, thick, composed, except on the borders, of two or three superimposed layers of large porous cells without leaf-green, these separated by a layer of simple, narrow cells containing leaf-green.

Veil (calyptra).--Large, split on one side.

Spore-case.--Erect.

Pedicel (seta).--Short.

Lid (operculum).--Plane at the base with an oblique and awl-shaped beak.

Teeth (peristome).--Eight, short, broadly lance-shaped, paleyellow and transparent.

Spores.--Mature in spring.

Distribution.--Common in the warmer parts of the world except Europe.

Genus CERATODON, Brid.

The species of this genus are small erect plants growing in bright or dark-green cushions on soil or in the crevices of rocks.

The leaves are lance-shaped and keeled, with entire or toothed margins, and a vein extending to or beyond the apex.

The mature spore-cases are long-egg-shaped, erect or slightly arched, with a short neck. They are dark or pale-red with wine-red or yellow pedicels, and short-beaked, conical lids, becoming deeply furrowed, inclined, and contracted below the mouth when old.

There is but one row of teeth, each tooth being cleft into two equal and strongly jointed segments, which suggest the generic name Ceratodon, a compound of two Greek words, , a horn, and a tooth. The two characteristics by which one may feel sure that his moss is a horn-tooth, are the cleft teeth and the shape and grooving of the spore-cases.

There are eighteen species in all, one common in North America.

The Purple Horn-tooth Moss, Ceratodon purpureum, Brid.--See Colour Plate IV.

Habit and habitat.--Look for the Purple Horn-tooth Moss on rocky ledges in open sunny places of the woods, in pastures and along roadsides, and in vacant city lots. Bright-green cushions of this moss may be found in depressions of the rocks during February and March. At this time the pedicels are often numerous and well-grown and their wine-red colour makes the moss conspicuous even while the spore-cases themselves thus early in the season are but little larger in diameter than the pedicels and are concealed by their veils. With the approach of warmer weather they mature rapidly still carrying their transparent veils. These are discarded before a great while and then the spore-cases and their conical short-beaked lids are glossy and wine-red. Later the lids fall, exposing a fringe of horn-like teeth about the rim. The spore-cases finally become deeply furrowed, inclined, and contracted below the mouth and in this condition may be found during most of the year.

Name.--The specific name purpureum is the Latin for "purple," It refers to the colour of the spore-cases and pedicels.

Plant (gametophyte).--Slender, erect, branching from the base of the pedicels; stems 1/2 to 3 inches long.

Leaves.--Lance-shaped, keeled; vein extending to or beyond the apex; margin somewhat irregularly toothed reflexed, opaque; surface with slight protuberances; cells distinct.

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

Veil (calyptra).--Smooth, transparent, split on one side.

Spore-case.--Long, egg-shaped with a short neck, dark-red, erect, somewhat arched; four- or five-angled and deeply furrowed when dry.

Pedicel.--Slender, wine-red, erect.

Lid (operculum).--Conical, short-beaked.

Teeth (peristome).--Purple, each split into two equal, strongly cross-barred segments, with tiny projections toward the apex.

Annulus.--Large, rolling back as the lid falls.

Spores.--Mature in early spring, when they are ousted by the shrinking of the wall tissue.

Distribution.--Almost universal.

Variety Xanthopous.--Greek yellow, and a foot; has a pale-yellow pedicel.

Variety Aristatus.--Latin "awned"; has the spore-case and pedicel pale and the mid-vein of the leaf extending beyond the apex of the leaf blade.

Variety Minor.--Latin "smaller"; is said to have narrower teeth jointed only from the middle downward.

Genus POTTIA, Ehrh.

The species of this genus are small and grow in tufts or cushions on the ground or in crevices of rocks. The stems are simple or sparingly branched from the base. The leaves are oval to oblong and obovate, soft, opaque, smooth or covered with tiny projections; the apex is usually taper-pointed, or hair-pointed; the base transparent; the vein round in section.

The cylindrical to obovate spore-case has sometimes a very short pedicel and sometimes a long one. The peristome may have imperfect teeth or none or sixteen tiny flat ones.

There are about eighty-three species in all, fourteen in North America.