Some forms, like Marchantia and Lunularia ([Fig. 57], C), produce little cups (x), circular in the first, semicircular in the second, in which special buds (H, I) are formed that fall off and produce new plants.
The highest of the liverworts (Jungermanniaceæ) are, for the most part, leafy forms like Madotheca, and represented by a great many common forms, growing usually on tree trunks, etc. They are much like Madotheca in general appearance, but usually very small and inconspicuous, so as to be easily overlooked, especially as their color is apt to be brownish, and not unlike that of the bark on which they grow ([Fig. 57], L).
Class II.—The True Mosses.
The true mosses (Musci) resemble in many respects the higher liverworts, such as Madotheca or Jungermannia, all of them having well-marked stems and leaves. The spore fruit is more highly developed than in the liverworts, but never contains elaters.
A good idea of the general structure of the higher mosses may be had from a study of almost any common species. One of the most convenient, as well as common, forms (Funaria) is to be had almost the year round, and fruits at almost all seasons, except midwinter. It grows in close patches on the ground in fields, at the bases of walls, sometimes in the crevices between the bricks of sidewalks, etc. If fruiting, it may be recognized by the nodding capsule on a long stalk, that is often more or less twisted, being sensitive to changes in the moisture of the atmosphere. The plant ([Fig. 58], A, B) has a short stem, thickly set with relatively large leaves. These are oblong and pointed, and the centre is traversed by a delicate midrib. The base of the stem is attached to the ground by numerous fine brown hairs.
The mature capsule is broadly oval in form ([Fig. 58], C), and provided with a lid that falls off when the spores are ripe. While the capsule is young it is covered by a pointed membranous cap (B, cal.) that finally falls off. When the lid is removed, a fine fringe is seen surrounding the opening of the capsule, and serving the same purpose as the elaters of the liverworts ([Fig. 58], E).
Fig. 58.—A, fruiting plant of a moss (Funaria), with young sporogonium (sp.), × 4. B, plant with ripe sporogonium. cal. calyptra, × 2. C, sporogonium with calyptra removed. op. lid, × 4. D, spores: i, ungerminated; ii–iv, germinating, × 300. E, two teeth from the margin of the capsule, × 50. F, epidermal cells and breathing pore from the surface of the sporogonium, × 150. G, longitudinal section of a young sporogonium, × 12. sp. spore mother cells. H, a small portion of G, magnified about 300 times. sp. spore mother cells.
If the lower part of the stem is carefully examined with a lens, we may detect a number of fine green filaments growing from it, looking like the root hairs, except for their color. Sometimes the ground about young patches of the moss is quite covered by a fine film of such threads, and looking carefully over it probably very small moss plants may be seen growing up here and there from it.