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times nearly two inches long. The base is either truncate or
slightly cordate; sometimes where there is a transition from
compound to simple pinnæ, a pinna will be found conspicuously
auricled on both sides, or on the upper side only.
Forked pinnules are occasionally seen.
The margin is continuously recurved to form a rather
broad involucre, and the very edge is somewhat thinner and
whiter. The veins are pinnately arranged on both sides of
the midvein, and fork about twice before reaching the margin.
The upper part of the veinlets is covered with sporangia,
which as they ripen push out from beneath the
involucre. The spores are obscurely tetrahedral and trivittate,
as in the other species of the genus.
This fern very often grows in company with Camptosorus
rhizophyllus, and its root-stock is often hidden beneath mosses
of the genus Anoniodon: it takes kindly to cultivation,
especially if it be planted in the crevices of calcareous rock-
work. It may occur on other than calcareous rock, but I
have never seen it on either granite, sandstone or basalt.
Names for varieties of this species have been proposed
by Pursh, and by Fournier, but the characters assigned do
not seem sufficiently distinctive.
Plate LIV., Fig. 4-7. — Pellæa atropurpurea. Fig. 4 is a plant of
ordinary size. Fig. 5 is a seedling. Fig. 6 is a pinna, enlarged, and
Fig. 7 a spore.
P l a t e LIV. — F ig . 8 - 1 0 .
P E L LÆ A G R A C IL IS , H o o k e r .
Slender Cliff-Brake.
P e e l æ a g r a c i l i s : — Root-stock slender, creeping, cordlike,
scantily furnished with little ovate appressed scales;
stalks scattered, slender, a span long or less, brownish-stramineous,
somewhat shining, darker and slightly chaffy at the
base; fronds two to four inches long, thin and tender, smooth,
ovate or ovate-oblong, pinnate; pinnæ few, the lower two to
four pairs once or twice pinnatifid, the uppermost simple; segments
of the sterile fronds-adnate-decurrent, roundish-obovate,
crenately lobed and toothed; those of the taller fertile fronds
lanceolate or linear-oblong, and more distinct, entire or auricled,
terminal ones longest; veins rather distant, mostly once
forked; involucre broad and continuous, delicately membranaceous.
Pellæa gracilis, H o o k e r , Sp. FIL, ii., p. 1 3 8 , t. cxxxiii, B .— E aton ,
in Gray’s Manual, ed. v., p. 6 5 9 ; Ferns of the South-West,
p . 3 1 9 .— H o o k e r & B a k e r , Syn. Fil., p. 14 5 .— P o r t e r &
C o u l t e r , Syn. FI. Colorado, p . 1 5 3 .
Pteris gracilis, M i c h a u x , FI. Bor.-Am., ii., p. 2 6 2 . — S w a r t z , Syn. FiL,
p. 99 . — W i l ld e n o w , Sp. PL, v ., p. 3 7 6 .— P u r s h , FL Am.
Sept., ii., p. 6 6 8 .— H o o k e r , FL Bor.-Am., ii., p, 26 4 .
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