Another important tribe of flowerless plants, to which we must be content with merely giving the general characters, for in a volume primarily intended as a guide to wild-flowers we must not occupy too much space with plants that do not produce flowers. At the same time, we believe the non-botanical among our readers will be glad to have a slight introduction, upon the strength of which they may cultivate the closer acquaintance of a most beautiful and interesting group of plants. A. Three-cornered Hypnum (Hypnum triquetrum) is a common species on woodland banks, growing in branching tufts. The stems are well clothed with leaves, which consist of a single layer of cells; there is therefore no necessity for the breathing pores (stomates) found on the leaves of flowering plants and giving access to the tissues beneath the cuticle. The leaves of mosses are not provided with stomates; neither are they stalked, but attached directly to the stem by their base. From the sides of the stem at intervals a number of brown, hair-like threads are given off, and each of these ends in a brown, pear-shaped nodding organ, the spore capsule. These capsules are each closed with a lid (operculum), beneath which is a double row of teeth, their tips directed towards the centre of the mouth. When the spores are ripe the operculum is cast off, and these teeth erect themselves to allow the minute spores to escape. The teeth (forming the peristome) of mosses are always some multiple of four; in Hypnum each row contains sixteen. B. Beautiful Hair-moss (Polytrichum formosum) represents another division of mosses in which the fruits are borne on the termination of the stem or principal branches. In an earlier condition than that figured the capsule is covered with a conical densely-hairy cap (calyptra); this is thrown off when the spores are ripe, the operculum follows and the spores are cast. |