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Four-toothed Mosses — Part 2

Genus TETRADONTIUM, Schwaegr.

This genus was established by Schwaegrichen, but differs so little from the genus Georgia that many think it should not be considered a separate genus. There are two species in all, one in North America.

It differs from Georgia in having both teeth and stems shorter, in having the spore-case oval instead of cylindrical and in having the veil cover the spore-case.

The name is derived from the Greek four, and a tooth.

Tetradontium repandum, Schwaegr.

Habit and habitat.--Very small, growing in loose clusters on shaded rocks.

Name.--The specific name repandum, the Latin for "curved," refers to the margin of the mouth of the spore-case.

Plant (gametophyte).--Stems very short, bearing little gemmae at the base of thread-like leafy branches.

Leaves.--Ovate-lance-shaped, rigid, red-brown, closely overlapping like shingles.

Leaves at the base of the pedicel (perichoetial leaves).--Ovate and oblong, very concave, vein obscure; scales about the male flowers (perigonium) smaller, thinner, vein absent.

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

Veil (calyptra).--Conical, resembling a bishop's mitre and covering the spore case to the base.

Spore-case.--Thick, oval, the margin of the orifice somewhat notched between the teeth.

Pedicel (seta).--Thick and rigid.

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

Teeth (peristome).--Simple, of four short, triangular teeth.

Spores.--Mature in autumn.

Distribution.--Near Glen House and at Dixville Notch, White Mountains. Very rare.

Genus SCHISTOSTEGA, Mohr

The Genus Schistostega contains but one species; this is found growing in bright-green patches on the ground in caverns and grottoes and under the shade of rocks. The protonema is persistent, and shines with a weird light in the semi-darkness where it grows. The most striking character of the moss is the highly refractive power of the protonema cells. These are able to converge the feeble rays of light which enter the caves and grottoes so that they fall upon the chlorophyll grains and enable them by light-energy to build up plant foods from gases and water. When searching for this moss one must be careful not to intercept the rays of light which enter the cave and then one may be fortunate enough to get the feebly reflected rays which emerge from it. The four diagrams if taken in order with their legends, will give one a clear idea of how the light rays are refracted and reflected by the cell-contents and of how the chlorophyll grains move to that part of the cell which is illuminated.

Schistostega osmundacea, Web. & Mohr.

Plant (gametophyte).--Living but one year, produced from a persistent, thread-like growth (protonema); stems tender and delicate, usually simple, 1/4 of an inch high with root-like filaments at the base. Two forms are found, the barren which are naked below and have two rows of vertically placed leaves above, the fertile which resemble the barren or are naked except for a small tuft of terminal leaves.

Name.--The specific name osmundacea suggests a resemblance to the ferns of the same name.

Leaves.--Oblong-pointed, confluent at the base; cells large, rhomboidal, containing leaf-green.

Habit of flowering.--Male and female on separate plants (dioicous) male flower -clusters bud-like.

Veil (calyptra).--Minute, narrow, resembling a bishop's hat, covering the lid only.

Spore-case.--Small, almost spherical, soft.

Spore-sac (sporangium).--Distinct.

Columella.--Present, thick.

Pedicel.--Long and soft.

Lid (operculum).--Small, convex, with a red border.

Teeth (peristome).--None.

Spores.--Minute, maturing in the spring.

Species.--But one known.

Distribution.--It has been found in northern and central Europe and in New York and the White Mountains.