Sporangia large, ovoid, striate-rayed at the apex, opening by a longitudinal cleft, naked, vertically sessile in a double row along the single vein of the narrow divisions of the pinnate (or radiate) fertile appendages to the slender and simply linear, or (in foreign species) fan-shaped or dichotomously many-cleft fronds (whence the name, from σχίζω, to split).
1. S. pusílla, Pursh. Sterile fronds linear, very slender, flattened and tortuous; the fertile ones equally slender (¼´´ wide), but taller (3–4´ high), and bearing at the top the fertile appendage, consisting of about 5 pairs of crowded pinnæ (each 1–1½´´ long).—Low grounds, pine barrens of N. J.; very local. Sept. (Also in Nova Scotia and Newf.)
20. LYGÒDIUM, Swartz. Climbing Fern. ([Pl. 20.])
Fronds twining or climbing, bearing stalked and variously lobed (or compound) divisions in pairs, with mostly free veins; the fructification on separate contracted divisions or spike-like lobes, one side of which is covered with a double row of imbricated hooded scale-like indusia, fixed by a broad base to short oblique veinlets. Sporangia much as in Schizæa, but oblique, fixed to the veinlet by the inner side next the base, one or rarely two covered by each indusium. (Name from λυγώδης, flexible.)
1. L. palmàtum, Swartz. Very smooth; stalks slender, flexile and twining (1–3° long), from slender running rootstocks; the short alternate branches or petioles 2-forked; each fork bearing a round-heart-shaped palmately 4–7-lobed frondlet; fertile frondlets above, contracted and several times forked, forming a terminal panicle.—Low moist thickets and open woods, Mass. to Va., Ky., and sparingly southward; rare. Sept.
21. OSMÚNDA, L. Flowering Fern. ([Pl. 20.])
Fertile fronds or fertile portions of the frond destitute of chlorophyll, very much contracted, and bearing on the margins of the narrow rhachis-like divisions short-pedicelled and naked sporangia; these are globular, thin and reticulated, large, opening by a longitudinal cleft into two valves, and bearing near the apex a small patch of thickened oblong cells, the rudiment of a transverse ring.—Fronds tall and upright, growing in large crowns from thickened rootstocks, once or twice pinnate; veins forking and free. Spores green. (Osmunder, a Saxon name of the Celtic divinity, Thor.)
[*] Sterile fronds truly bipinnate.
1. O. regàlis, L. (Flowering Fern.) Very smooth, pale green (2–5° high); sterile pinnules 13–25, varying from oblong-oval to lance-oblong, finely serrulate, especially toward the apex, otherwise entire, or crenately lobed toward the rounded, oblique and truncate, or even cordate and semi-auriculate base, sessile or short-stalked (1–2´ long); the fertile racemose-panicled at the summit of the frond.—Swamps and wet woods; common. The cordate pinnules sometimes found here are commoner in Europe. May, June. (Eu.)
[*][*] Sterile fronds once pinnate; pinnæ deeply pinnatifid; the lobes entire.