CLASS III.
Trachea-plants—Ferns.
1562. At first a fascicle only of spiral vessels can originate, which is necessarily surrounded by cellular tissue, and therefore lies in the middle of the plant. Such plants are the Filices or ferns.
1563. As the spiral vessels are the antetype of the leaves, so does the trunk here obtain the form of the leaf, without itself producing true leaves. For, in the ferns, the fruits lie upon the back of the apparent leaf, which can only be the trunk.
1564. The fruits, being further removed from the fungi, no longer spring up in an opercular, but in a valvular, manner like the higher capsules.
1565. Green plants with imperfect spiral vessels and blossoms, and also with naked seeds devoid of true capsules, belong to the class of Ferns.
1566. I therefore place in this class the Coniferæ or trees with acicular foliage, because they have no ovarium, but naked seeds; and besides these, some other plants, though doubtfully, on account of their very abortive blossoms, as the Naiadaceæ. There are therefore Tracheal plants without and with stamina. The first portray the stock or trunk, the second, the thyrsus or blossom; they live mostly in dry situations, and produce resins or fetid matters.
1567. First order. Parenchymatous ferns—Aquatic ferns. I here place the aquatic ferns, because, as water-plants, they occupy a lower situation, because they support the fruits upon a radical trunk, and finally, because these fruit-vesicles have two kinds of contents, all of which seems to remind us of the fuci and lichens; they correspond to the Tremellini.
1568. Second order. Sheath-ferns—Club-ferns. Here commence the land ferns, and those kinds indeed whose so-called capsules open in a valvular manner, just as in the liverworts; or almost after the fashion of a pyxidium by an orifice, somewhat as in the mosses; the trunk is provided with squamose leaves or lobes, e. g. Lycopodiaceæ and Osmundaceæ; they correspond to the Confervaceæ.
1569. Third order. Stem-ferns—Annular or Ring-ferns. Here we meet with phylloidal involuted capsules or seeds upon the back of a stem that is likewise leaf-like; e. g. the typical or true ferns.