The genus Adiantum contains eighty-three species, according to Mr. Baker’s estimate; but this number is reduced to sixty-seven by the more recent and very careful recension of Keyserling. The species vary in form from a simple and reniform frond an inch or two in diameter to others with ample tripinnate and even quadripinnate fronds. The species with distinctly bipartite and radiated fronds are Ad. patens, hispidulum, and fiabellulatum. A. patens is found in Mexico and Central America. It is a smaller plant than A. pedatum, and has deeply-sunken reniform involucres. The other two occur in South-eastern Asia, the hispidulum extending to Africa and to New Zealand, and the flabellulatum to Japan: the former has hispid surfaces and small roundish involucres; and the latter has rusty-fibrillose rachises, coriaceous pinnules, and transversely oblong sub-confluent involucres. Ad. patens follows the form and branching of our fern very closely; but the two Old-World species often depart from it, and show a tendency to develop branches on one or other of the longest pinnæ, thus indicating an approach towards a pyramidal structure of the frond.
The remaining Adianta of the United States are Ad. Capillus-Veneris (Linnæus), found from North Carolina to California; Ad. emarginatum (Hooker), which is the Ad. Chilense of American botanists, but not of Kaulfuss, found in California and Oregon; and Ad. tricholepis (Fée), which occurs in Texas and California, and extends southwards to Central America.
The American Maiden-hair is easily cultivated, and will grow very freely either in a shaded corner of a garden or in the house, and is perhaps more elegant and graceful than any other of our ferns, the climbing-fern scarcely excepted. Josselyn evidently mistook it for the Venus-hair, one of the chief ingredients in a syrup which was formerly a famous remedy for nearly all ailments, and said, “The Apothecaries for shame now will substitute Wall-Rue no more for Maiden Hair, since it grows in abundance in New-England, from whence they may have good store.”
Mr. Emerton’s figure is taken from a living plant, and shows the frond as it appears before it has been flattened in a collector’s portfolio.
OSTRICH-FERN.
ONOCLEA STRUTHIOPTERIS, Hoffmann.
Ostrich-Fern.
Onoclea Struthiopteris:—Caudex short, thick, erect, emitting slender subterranean stolons; stalks stout, a few inches to a foot long, chaffy at the base; fronds standing in a vase-like crown, dimorphous; sterile ones one to ten feet high, herbaceo-membranaceous, broadly lanceolate, narrowed from the middle to the base, abruptly short-acuminate, pinnate; pinnæ very many, sessile, the lowest ones sinuate and deflexed, the rest three to eight inches long, five to nine lines wide, linear-lanceolate, acuminate, deeply pinnatifid into numerous close-placed oblong obtuse entire segments provided with a midvein and several simple veinlets on each side; fertile fronds in the middle of the crown or vase, much shorter than the sterile, rigid, contracted, narrowed at the base, pinnate; pinnæ one to two inches long, crowded, obliquely ascending, linear, obtuse, sub-entire or pinnately lobed, the lobes one or two lines long and broad, the margins much recurved, and the whole pinna forming a somewhat articulated pod-like body; veinlets of the fertile segments few, soriferous on the back; receptacle elevated; indusium very delicate, lacerate-toothed, half surrounding the sorus; sporangia at length confluent and filling the fertile pinnæ.
Onoclea Struthiopteris, Hoffmann, “Deutschlands Flora, p. 11 (1795).”—Swartz, Syn. Fil., p. 111.—Weber & Mohr, Taschenbuch, p. 47, t. iv., f. 3, 4.—Schkuhr, Krypt. Gew., p. 97, t. 105.—Mettenius, Fil. Hort. Lips., p. 97, t. xvii., f. 11-15.—Milde, Fil. Eur. et Atlant., p. 154.
Onoclea nodulosa, Schkuhr, Krypt. Gew., p. 97, t. 104 (Perhaps also of Michaux, but this is still uncertain).