OF THE REPRODUCTIVE ORGANS OF FOLIOSE ivIUSti.
THE flowers of mosses are in most instances moncc cious ; in a considerable number are they dicecious ; very rarely are they polygamous (Bryum palustre); and equally rarely are they bisexual or united (Bartramia porniformis, Bryum trichodcs.) Mosses in general are fond of growing in tufts, parti cularly the diclinous species. So closely are the male and female plants of Gymnostomum Kr:forme frequent ly placed together, that, on a cursory view, they may ap pear to spring from the same rout.
In regard to situation, the flowers of mosses arise either from the base of the stem, from its apex, along its sides; or from the apex or sides of the branches. To give instances of some of these modes of distribu tion : In Dicranum taxifolium the female flowers arise from the root ; the male are axillary. In the genus Phascurn, the female flowers are terminal, the male (usually very ininute,) are axillary. In Hypnum tri quetrum, a dicecious species, the male flowers appear chiefly on the sides of the branches, the female on the sides of the stem. In H. proliferum, both male and fe male flowers grow from the sides of the stem. In the genus Sphagnum, the male flowers are found in the in crassated apices of the upper branches, the female aro axillary.
Though the flowers of mosses are minute, they may, with few excep.ions, be easily discovered by an eye somewhat practised, either witnout any assistance, or with the aid of a common pocket glass.
The flowers of mosses, as of other plants, consist of the essential parts of fructification, and their envelopes.
The envelope of the flowers of a moss is termed Pe richmtium. It is usually polyphyllous. but the male flowers of Encalypta vulgai is, and a few other species, have a four-leaved perim,xtium. The number ol leaves in the perichmtium of different species, varies Iron] six to twenty. The perichaetial leaves are seldom in a single row. When in severat rows, the outermost are usually smaller than the intermediate, and the innermost are the smallest. Except in some fuw instances, in which those
surrounding the female flowerts are similar to those of the stem, the intermediate and inner, (and sometimes also the outer perichxtial leaves) alinost invariably differ very much in structure, form, and sometimes in colour and margin, from those of the stem. Thus in Encalypta vulgaris, and ciliata, the perichxtial leaves want the very prominent nerve of the stem leaves, and are altogether unlike them in form. Peculiarities in the perichxual leaves of Dicranum bryoides, and DIphyscium follosutn, have already been mentioned; and it rnay now be adckci, that while the interior perichxtial leaves in Diphysium foliosum divide at the summit into cilia, the exterior are acuminate, and the stem leaves are tongue-shaped. It would appear, also, that in Buxbaumia aphylla the leaves are of two different sorts. Those with which we have been for sonic time acquainted, and of which we examin ed .a very considerable number in October, 1819, are reticulated, the cells usually hexagonal or oval ; much more rarely, we conceive, oblong, as they are represented in Mr. Greville's accompanying figure. The other sort, which we conceive to be periclixtial leaves, were dis covered by Air. Greville, while he was drawing the figures for this paper. They have the appearance of a number of conferva-like filaments, united in a single file. These leaves, like the others, are lacitliated; and the lacinim are formed by the separation of the fila ments into sets of two or three ; and sometimes a single one goes to the formation of a segment by itsell In the lacinix, the filaments sometimes again separate to wards the summit. With these leaves we are quite unacquainted ; but we can rely on Mr. Greville's ac curacy. The Hypna in general have the female flowers surrounded by a perichxlium consisting of mentheana ceous, transparent leaves, extremely different frotn those of the stem.