Probably the earliest notice of the walking-leaf is in Ray’s “Historia Plantarum,” vol. ii., p. 1927, published in 1688. It is there called “Phyllitis parva saxatilis per summitates folii prolifera.” Other early accounts may be found in the “Species Plantarum” of Linnæus and of Willdenow, and in the second edition of Gronovius’s “Flora Virginica.” In the latter work it may be seen that Gov. Colden long ago described the auricles as being “also often acuminate.”
A second species, with membranaceous fronds acute at the base (C. Sibiricus), occurs in Northern Asia, but is apparently very rare.
ASPLENIUM PINNATIFIDUM, Nuttall. Pinnatifid Spleenwort.
Asplenium pinnatifidum:—Root-stock short, creeping, branched; stalks numerous, clustered, brownish near the base, green higher up; fronds six to nine inches high, herbaceous or sub-coriaceous, mostly erect, lanceolate-acuminate from a broad and sub-hastate base, pinnatifid; lower lobes roundish-ovate or rarely caudate, sometimes distinct, the margin crenated, the upper ones gradually smaller and more and more adnate to the winged midrib; the uppermost very short, and passing into the sinuous-margined long acumination of the frond; veins dichotomous or sub-pinnate and forking, free; sori few on the lower lobes, solitary on the uppermost, those next the midrib occasionally diplazioid.
_Asplenium pinnatifidum_, Nuttall, Genera of N. Amer. Plants, ii., p. 251.—Kunze, in Sill. Journ., July, 1848, p. 85.—Gray, Manual.—Eaton, in Chapman’s Flora of Southern U. S., p. 592.—Hooker, Icones Plantarum, t. 927; Sp. Fil., iii., p. 91.—Mettenius, Fil. Hort. Lips., p. 72, t. 10, figs. 1, 2; Asplenium, p. 126.—Hooker & Baker, Syn. Fil., p. 194.
_Asplenium rhizophyllum_, var. _pinnatifidum_, Muhlenberg, Catalogus Plant. Am. Sept., ed. ii., p. 102.—Barton, Compendium Floræ Philad., ii., p. 210.—Eaton,[3] Manual of Botany, ed. iii., p. 188, etc.—Torrey, Compendium, p. 383.
Hab.—Discovered by Thomas Nuttall in crevices of rocks along the Schuylkill River, near Philadelphia; also found along the Wissahickon Creek in the same vicinity. Lancaster County, Pennsylvania, Prof. Thomas C. Porter. On moist cliffs of sandstone in the Cumberland Mountains, East Tennessee, Prof. F. H. Bradley. Hancock County, Alabama, Hon. T. M. Peters. Mine-la-Motte, Southern Missouri, on sandstone rocks, Dr. Engelmann.