FILICES, ferns, one of the seven fami lies or natural tribes into which the Whole vegetable kingdom is divided by Linn limns, in his " Philosophia Botanica." They are defined to be plants which bear their flower and fruit on the back of the leaf or stalk, which, in this class of int perfect plants, are the same. In the Sexual System, the ferns constitute the first order, or secondary division of the twenty-fourth class, Cryptogamia; in Tournefbrt's Method, they are the six teenth class; and in Ray's the fourth, under the name of Capillares. Haller denominates them Epiphyllospermm, that is, plants that bear their seeds on the back of the leaf: others term them Acaules, because they have properly no stem. These plants in figure approach the more perfect vegetables, being furnished, like them, with roots and leaves. The roots creep and extend themselves horizontal ly under the earth, throwing out a num ber of very slender fibres on all sides. The stem in these plants is not to be dis tinguished from the common foot-stalk, or rather middle rib of the leaves ; so that, in strict propriety, the greater num ber of ferns may be said to be Acaules, that is, to want the stem altogether: in plants of the second section, however, the middle rib, or stalk proceeding from the root, overtops the leaves, and forms a stem, upon which the flowers are sup ported. The leaves proceed either sin
gly, or in greater numbers, from the ex tremities of the branches of the main root. They are winged, or hand-shaped, in all the genera, except in adder's-tongue, pepper-grass, and some species of spleen wort. The flowers of the ferns, what ever be their nature, are in the greater number of genera fastened, and as it were glued to the back of the leaves; in some they are supported upon a stem or stalk, which rises above the leaves, and is ei ther, as we said above, a prolongation of their middle rib, or issues out of the cen tre of the plant, unconnected with the leaves altogether. From these different modes of flowering arise the two sections, or divisions, of this natural order, -viz. I. those in which the parts of fructification grow upon the leaves ; 2. those in which the flowers are borne upon foot-stalks that overtop the leaves.