19. ONOC'LEA, L. Sensitive Fern. (Gr. , a kind of vessel, to close.) Fronds sterile and fertile; sori clustered, confluent; proper indusium very thin, lateral; common indusium formed of the segments of the frond, whose margins are revolute and contracted into the form of a berry, opening, but not expanding. - Sterile fronds deeply pinnatifid, ample; fertile bipinnate, with recurved and globular, contracted segments.
O. sensibilis L. Common in low grounds. Fronds about a foot high, the barren ones broad and somewhat triangular in outline, composed of broad, oblong, sinuate divisions, the upper ones smaller, nearly entire, becoming united at base. The fertile frond is very dissimilar in its form to the others, resembling a compound spike enclosing the fruit in the globular segments of its short division?, Color dark brown. Jl. - Very sensitive to frost.
β. obtusilobata Torr Fertile frond segments leaf-like, only partially revolute, not concealing the sori. - Mass., N. Y., very rare. (O. obtusiloba Schk.)
20. ASPID'IUM, L. Shield Fern. (Gr. a small shield; from the resemblance of the indusium.) Sori orbicular, scattered, terminal or lateral on the pinnate veins; indusium orbicular, peltate or reniform with a deep sinus, covering the sorus, opening all around.
§ Upper half of the frond fruitful, contracted, unlike the lower sterile half.......
Nos. 1, 2
§ Upper half of the frond like the lower, not contracted, (a)
a Frond simply pinnate, lfts. ovate, semiauriculate..............
a Frond bipinnate, segments semiauriculate, sharp-toothed.........
Nos. 4, 5
a Frond bipinnate, segments equilateral, deeply pinnatifid............
a Frond pinnate with pinnatifid leaflets, (b)
b Sesrmcnts suhcoriaceous. with the sori near the midvein...........
Nos. 7, 8
b Segments subcoriaceous, with the sori at the margin.....................
b Segments soft and thin, - smoothish. Sori in 2 rows..............
Nos. 10, 11
- hairy. Sori without order....................
1 A. acrostichoides Willd Leaflets of the frond undivided, subsessile, falcate-lanceolate, auriculate on the upper side at base, ciliatc-serrulate, only the upper ones fertile; sori at length confluent; stipe chaffy. - Common in rocky shades. Frond 15 - 18' high, of a narrow-lanceolate outline. Stipe with loose, chaffy scales. Leaflets numerous, slightly curving upwards, 1 - 2' in length, (incised in A. Schweinitzii Beck), the terminal ones, which alone are fruitful, are contracted in size, th3 under side becoming overspread with the sori. June - Aug.
2 A. Ludovicianum Biddell. Frond tall (2 to 4f), rigidly erect, narrowly oblong-lanceolate in outline, pinnate and barren below, bipinnate, fruitful and contracted above; lower lfts. incisely pinnatifid with very obtuse, subentire lobes, upper with distinct, oblong, obtuse, crenate-serrate segments; indusia peltate, in 2 intra-marginal rows. - Swamps, Ga., Fla. to La. The short stipe and long rachis chaffy.
3 A. lonchitia Willd. Frond pinnate, linear-lanceolate in outline, rigidly erect
(8 to 12'); lfts. obliquely triangular-ovate, auricled on the upper side at base, largest (1' long) in the middle, gradually reduced above and below to the base, all beset with close, spiny teeth, and covered with fruit beneath. - N. Mich. Br. Am.
4 A. aculeatum Swtz. Segments of the leaflets ovate, subfalcate, acute, aculeate-serrate, truncate and auricled on the upper side at base, upper leaflets fertile; stipe and racbis chaffy. - Mansfield Mt., Vt., and Mts. in Essex Co., N. Y., (Macrae). Fronds dark green, in tufts 1 - 2f high. Segments of the leaflets on very short petioles, somewhat dilated at base on the upper side, deeply serrate, each serrature tipped with a short spinous bristle. Sori in rows, distinct. Aug.
5 A. fragrans Swtz. Frond coriaceous, pinnate with deeply pinnatifid or pinnate lfts., lance-ovate in outline, glandular and fragrant; lfts. narrow-pointed, with a dozen pairs of small, obtuse, bristly serrate segments which are unequal at base; indusia large, orbicular, peltate, covering segments. - Rocks, Penokee Iron Range, L. Sup. (Lapham) and northwest. Frond 6 to 12' high. Stipe and rachis chaffy.
6 A. spinulosum Willd. Leaflets oblong-lanceolate, distinct; segments distinct, oblong, obtuse, incisely pinnatifid; ultimate segments mucronate-serrate; stipe chaffy; indusium umbilicate. - Woods and shady pastures. Fronds 1 - 2f high, nearly tripinnate, the foliage about twice as long as wide, acuminate at apex, abrupt at base. Leaflets also acuminate, but the segments rather obtuse, all distinct at base, except those near the summit, serratures with short, soft bristles. Stipe with large, tawny scales. Sori large. Jl (A. dilatatum Swtz.) Variable.
7 A. Goldianum Hook. Goldie's Fern. Frond ample, oval or ovate, in outline (10 to 16' long, two-thirds as wide) pinnate, as long as the smooth stipe; lfts. broad-linear, alternate, deeply pinnatifid, crenate-appfessed-serrate, acutish, with 2 rows of distinct fruit-dots near the midvein; indusium reniform-peltate. - A large Fern in rocky woods, N. and W. States and Can. Lfts. close together) about 30 pairs, with about 20 pairs of segments. Stipe chaffy at base, scarcely so above.
8 A cristatum Swtz. Stipe with a few large, oblong, torn scales, chiefly at base; frond narrowly lanceolate; leaflets deeply pinnatifid, remote, short-petiolu-late, broadest at base, the lower triangular-ovate; sori large, in a single row each side the midvein of each dentate segment; indusium fixed near one side. - Woods. Can., N. H. (Rickard) to N. Y. and N. J. A beautiful Fern, 20 to 30' high. Frond dark green, 15 - 18' by 5 - 8'. Leaflets gradually narrowing from base to apex. Segments nearly distinct, more or less distinctly serrate-dentate, each with 1 - 25 dark-brown sori (lower leaflets fruitless). July. (A. Lancastriense Spr.)
9 A. marginale Swtz. Marginal Shield-Fern. Segments of the leaflets oblong, obtuse, decurrent, crenate-sinuate, repand at base, lower ones almost pinnatifid; sori marginal; stipe chaffy. - A large, handsome Fern, in rocky woods, common. Frond 12 - 18' high, very smooth (rachis a little chaffy), its divisions nearly opposite. Segments of the leaflets distinct, near an inch long, 1/4 as wide, contracted at base, then decurrent, forming a narrow margin along the rachis. Fruit in round dots, in regular rows along the margins of the segments. Indusium large, orbicular, with a lateral sinus. July.