BRYOPHYTES (Gk. bryon, a mossy seaweed, blossom 4- phyton. plant 1. One of the four primary groups of the plant kingdom, containing the two great divisions popularly known as Mosses (Iinsei) and Liverworts Int-. potira) . The liverwort,: arc considered to have been derived in sione way from the green Alg:c, and to have given rise in torn to the musses. It is the liverworts, therefore Ni hieb represent the transition between the aquatic life of .\lge and the terrestrial life of must. Bryophytes. As a consequence of this transition from the aquatic to the terrestrial habit, great changes in structure were prodnecd, so that the Bryophytes an. \ cry different from the Alga•.
one of the most important facts connected with Bryophytes is the distinct Alternation of orations (q.v.) which they exhibit. The group is also distinguished by the free and many-eelled sex-organs. The antheridimn (male organ) is a body of various shapes, from ovoid to •lub shaped. and consists of a single layer of sterile cells, which serves as a wall; within this there is a compact mass of very small and numerous mother-cells, each one of which organizes a single hiciliated sperm. The sperm of Bryoldlytes Is one of their distinguishing characters, the body being small, little if at all curved, and always bearing two cilia. The archegonia are flask shaped organs, consisting of neck and venter, the latter containing the single large egg. See AN TlIERIORM and Aucut:coN The fertilized egg lies within the venter of the arehegonimn, and when it begins to germinate the venter also begins to increase in size and in character. In the true mosses the young sporo gonimn grows faster than the venter, and finally breaks it, carrying the whole top of the modi fied arehegoninin upon its apex like a cap. This loose cap may be found upon the capsules even when they are ready to shed spores, and is known as the calyptra. The gradual evolution of the sporophyte, from its simplest form in the liver worts to its most complex form in the true mosses, is of great morphological interest. The simplest sporophyte in Bryophytes is that of the liverwort known as Riccia, in which it con sists of nothing more than a capsule with a single layer of sterile cells for a wall, all of the cells within being devoted to the production of spores. As one passes from Riccia to the higher forms, there is a gradual diminution of the tissue de voted to the production of spores, and therefore a gradual increase of the sterile tissue. Finally, in the true mosses the sterile tissue far exceeds in mass the sporogenous, the former consisting of foot, seta. and the bulk of the capsule; while the latter is restricted to a single layer or two of cells within the capsule.
The opening (dchiseenee) of the capsule is also a matter of interest among the Bryophytes. In the lower liverworts the wall merely decays or bursts, liberating the spores. Among the leafy liverworts it splits into four distinct valves, N•hieh spread apart. Among the liver worts; of the genus Anthocc•os the capsule is elongated like a very slender pod and splits into two valves like a pea-pod. Among the mosses, however, a distinct lid Ooperenhon't is devel oped. which is pushed aside when the capsule is ready to discharge its spores. In the true mosses a further elaboration of the capsule usually oc curs in the formation of what. is vaned the •peri stome.' a set of tooth-like processes often of beau tiful pattern, which spring from the rim of the capsule and stretch toward the centre. These are hygroscopic, and by their curving in and straightening out help to loosen up the spores. Among the liverworts there is also a device for assisting in spreading and somewhat scattering rho spores. Certain mother-cells do not produce spores, but become modified into long tibre-like which are spirally thickened. These eells ae known as 'platers,' and by their jerking, .lumping movements when alternately moistened and dried they help to sutler the spores with which they are in coin:wt.
The sex-organs of Bryophytes are borne in a variety of ways. Ananig the liverworts they are lutes over the hack of the thallus body: in others they are collected in definite groups upon the body; in still others, as in Mar chantia, they are carried upon a special branch, at whose summit there is a disk in which they are developed. In the mosses the antheridia and the archegonia occur in clusters at the ends of main axes or branches. In some eases the anthe ridial and arehegonial clusters are separated; in others, the two organs are found in the same clus ter. The leaves at the tips which bear the sex organs become more or less modified, forming a rosette, and, usually being larger than the ordi nary leaves and sometimes differently colored, they have been called 'flowers! Among the sex organs, and especially among the antheridia, there often occur hair-like outgrowths, known as 'paraphysel:' (q.v.). For a further account of the two great groups of Bryophytes, see HEPATI C.E and Alusci.
In addition to the books cited under MOR PHOLOGY, all of which treat more or less fully of this group, consult Campbell, Mosses and Ferns (New York, 1395), which gives a more detailed account of the structure and development of Bryophytes. For works on classification, see au thorities referred to tinder TAXONOMY.