FILICES. (FERNS.) 595 
Var. dilatatum, Gray. Fronds wider in outline, of a rather firmer text- 
ure; the pinnz fewer and set farther apart, the lowest pair largest, with the 2-3 
lower basal pinnules elongated ; segments larger and more distant ;,fruit-dots 
larger; indusium smooth. (A. dilatatum, Swartz. A. campylopterum, Kunze.) 
— Summits of the Black Mountains, North Carolina, Rugel.— Fronds 19 - 2° 
long, 10/-16! wide. 
5. A. Ludovicianum, Kunze. * Fronds membranaceous, rather rigid, 
finely glandular-pubescent beneath on the midribs, ovate, acuminate, bipinnate ; 
pinnz distant, petioled, ovate or oblong, acuminate; pinnules ovate, deeply 
pinnatifid ; the lowest divisions sessile with a narrowed base; the upper ones 
adnate, oblong, obtuse, crenately appressed-serrate ; serratures acute, sometimes 
" denticulate ; fruit-dots half-way between the midrib and margin, on the upper 
branches of the forked veins; indusium reniform, thickish, entire, smooth, per- 
sistent.” Mettenius. — Florida to Louisiana, Kunze. — “ Rootstock oblique; 
fronds 2? -3? long; stipe straw-color, sparsely chaffy." — I have not seen this 
Fern, which has more recently been referred by Mettenius to A. Canariense, 
Al. Br. 
6. A. Floridanum. Fronds thickish, broadly lanceolate, pinnate ; lower 
pinnz sterile, triangular-lanceolate, deeply pinnatifid, with closely set oblong, 
obtuse divisions ; upper pinnze fertile, narrower and longer, again pinnate, with 
oblong obtuse pinnules, distant on the narrowly winged secondary rachis ; fruit- 
dots large, half-way between the midrib and margin ; indusium round-reniform, 
smooth. (Nephrodium Floridanum, Hook.) — Wet woods, Florida to Louisiana. 
— Fronds 1°- 2° high, the sterile ones shorter, growing in a crown from a 
thick and scaly rootstock.—The plant has much the appearance of large 
forms of A. cristatum, Swartz, and may prove to be an extreme state of that 
species. 
7. A. marginale, Swartz. Fronds evergreen, smooth, thickish and al- 
most coriaceous, ovate-lanceolate, bipinnate ; pinne lanceolate from a broad 
base ; pinnules oblong or linear-oblong, attached by a broad base to the nar- 
rowly winged secondary rachis, entire or crenately toothed ; fruit-dots large, 
very near the margin; indusium round-reniform, convex, thickish, smooth. — 
Mountains of North Carolina, and northward. — Fronds bluish-green, 19- 2° 
long, on a short stipe, which, like the short thick rootstock, is shaggy with large 
brown chaffy scales. 
§ 2. POLYSTICHUM, Roth, Schott. Indusium orbicular, fixed by the de- 
8. A. acrostichoides, Swartz. Fronds evergreen, thickish, smooth and 
shining, lanceolate, the fertile ones tallest, pinmate; pinne numerous, short- 
stalked, oblong-lanceolate, auriculate at the base on the upper side, cuneate at 
the lower, obtuse or acute, finely serrate or incised with spinulose-pointed teeth ; 
the upper pinnz of the fertile frond contracted and covered with the copious 
fraicdows coc round, peltate, smooth and etg n giga 
