Mosses
(Musci). These are well-known to everyone, at least a regards their general appearance. They possess distinct leaves and stems, the latter bearing below root-hairs, which act as roots for their benefit. All parts of the plants are made up of cells, without vessels among them; but some cells are long, and form a kind of central thread in the stem, and also a midrib in each leaf. Mosses vary in size from a little over 1/12in. (Buxbaumia) to several feet in length of stem (Fontinalis), but usually range between 1/2in. and an inch or two high. The leaves are always small, and are usually numerous. If the life history of any Moss be traced out, it will be found to be nearly as follows, if we commence with one of the minute one-clled spores. The spore pushes out a fine filament, which branches, and forms buds here and there on the branches; each bud grows larger, and forms a plant with stem and leaves. On this plant, at certain periods, grow parts that correspond in use to the young seeds (ovules) and the pollen of flowering plants. From their union, there results the so-called fruit of the Moss, or the capsule, usually supported on a stalk. The capsule, with its stalk, is really a new plant, imbedded by the base in the leafy plant, and nourished by absorbing sap from it. The capsule has usually a rod of tissue running up its centre, with a space all round between this and the sides, and in this space are formed the spores. When the spores are ripe, they are set free, either by slits formed in the sides of the capsule, or, more often, by a lid (operculum) falling off. Below this lid, there is usually a row (at times two rows) of membranous teeth, always in multiples of four, forming the peristome. In the classification of Mosses, considerable stress is laid on the nature of the peristome, and of its teeth.
Uses. The direct uses of Mosses to mankind are very few. In gardening operations "Moss" is largely used to maintain moisture around plants in pots, &c., or epiphytes, such as many tropical Orchids. This is a Sphagnum, or Bog Moss, a genus of which numerous species and varieties occur in Britain. Its peculiar power of absorbing moisture is due to many of the outer cells having openings into them, so as to permit free ingress and egress of the water, which is sucked up by the Moss, just as in a sponge. Sphagnum is also an excellent material for packing fragile articles which it is necessary to send, by train or by other means, to a distance. The various kinds of Sphagnum love low, swampy ground; they aid much in the formation of peat. Other uses of Mosses are but few and unimportant. Brushes are at times made of the stems of Hair Moss (Polytrichum).
Injuries. Direct injuries to man from Mosses are even fewer than direct benefits; but harm in gardens may result from Moss on trees, and on gravel walks, or on the soil of gardens, lawns, &c. Moss on gravel walks generally indicates damp sub-soil; good drainage is therefore essential for its prevention. If it appears, it may be kept within bounds by loosening the surface. Watering with a solution of copper sulphate (blue vitriol), or of corrosive sublimate, is useful if the walk is not of large extent. Moss on garden soil, and on lawns, is very hurtful in crushing out the plants that are of use, or are ornamental. Mosses do not thrive well in fully-drained soils, hence the drainage ought to be at once seen to when these plants begin to be troublesome in gardens. The soil may advantageously be top-dressed with lime, or with mixtures of lime and sulphur, or of soot and salt, or with compounds of ammonia, e.g., ammonium sulphate (1/2lb. to 1 gallon of water). Mosses and Lichens on trees may prove hurtful if closely covering the bark, since they keep it too moist, thus promoting the growth of parasitic Fungi under their shelter; and this may result in the death of the branches. Mosses and Lichens may also give shelter to parasitic insects, especially to Aphides, and to various Larvae during winter. The plants of Moss and Lichen themselves, probably, do not absorb any nourishment from the trees; yet, for the above reasons, they should be removed. This may be done by vigorous brushing after rain has fallen pretty heavily for some hours, as they are more loosely attached while soaked. The branches should be then well washed with a solution of soft soap and lime. Dead branches loaded with Lichens and Mosses should be removed. Newly-slaked lime may be scattered among the overgrowth with advantage. Excessive growth of such plants on branches of trees may be a good deal lessened by judiciously thinning plantations, and by pruning the individual trees, so as to insure free access of air and light.