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Leafy Mosses

"The tiny moss, whose silken verdure clothes

The time-worn rock, and whose bright capsules rise,

Like fairy urns, on stalks of golden sheen,

Demand our admiration and our praise,

As much as cedar, kissing the blue sky,

Or Krubul's giant flower. God made them all,

And what He deigns to make should ne'er be deemed

Unworthy of our study and our love."

All true mosses produce their spores in a spore-case of one shape or another which opens, with few exceptions, by a lid. The spore-case may be situated at the summit of the stem of the moss-plant or on one side of the stem. It may or may not be supported upon a pedicel (seta).

Many species of moss have two rows of teeth about the rim of the spore-case, while some have one row and some have none. The teeth may vary greatly in shape and number; as a rule, there are four, sixteen, thirty-two, or sixty-four.

The spore-case when immature is often covered by a cap or veil (calyptra). The veils vary in shape and in size, sometimes persisting a long time, sometimes falling away in the early stages.

All leafy mosses have leaves which may vary in size, in shape, in texture, in colour, and in the nature of the margin, this being sometimes entire, and sometimes toothed, sometimes with a thickened margin or with one made up of cells very different from those within.

The species of mosses are based on the characters of the plant, the spore-case, the pedicel, and the leaves, together with their habit of growth.

Everything about the moss-plants indicates that their purpose in living is to reproduce their kind. Each part is designed and perfected with this end in view. In the struggle for existence they have come to adapt themselves to the most varied conditions, but a certain amount of water is as necessary to them as to all other forms of life. Without water the male cells can never reach the egg-cells and the leaf-green (chlorophyll) cannot manufacture plant food. It is true that there are species which have ceased to attempt the formation of spores in localities where the rainy season is never long enough to permit their reaching maturity. In such species the plants become very dry, the leaves and branches break off and are blown hither and thither by the wind, each piece being capable of growing into a new plant, if it has moisture long enough to permit it to get well started. It can then endure long periods of drought and can avail itself of small quantities of moisture which may be condensed from the air.

It must be remembered that normally all plant food is manufactured by the green colouring matter in the leaves and stems of plants, and that these little agents can work only in the light. The light must not be too weak, or the leaf-green becomes yellow and cannot work; again the light must not be too strong or the leaf-green is destroyed and the water in the plant is too rapidly evaporated, with the result that the plant dies.

In order that moss plants may avail themselves of small quantities of water and may withstand the fierce heat of the sun, they have various interesting contrivances for folding their leaves so as to retain what moisture they have absorbed, and they have methods of transferring their delicate leaf-green from one part of the plant, too much exposed to the sun, to a part less exposed, or of surrounding the leaf-green-bearing cells in a wall of large colourless cells. This arrangement accounts for the fact that some mosses, as the peat-mosses (Sphagnum, Plate XI), white-mosses (Leucobryum, Colour Plate IV), and others appear light gray when dry and green when wet.

The luminous moss has given up the struggle for a place in the outer world and has retreated to caves where but a few rays of light enter. It has adapted itself to the semi-darkness by devising a method whereby it can converge the several feeble rays which fall upon it so that they form one beam sufficiently strong to permit their leaf-green to manufacture plant food.