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D e s c r i p t io n . — The habit of this fern is very dense, as the
specific name happily assigned to it by Brackenridge implies. It
grows in dense tufts among rocks ; and the pinnæ and segments
are so crowded as to overlap each other, and render it difficult to
see exactly what is the method of branching. The stalks are
usually less than a span long, rigid, dark-brown, and rather brittle.
The fronds are often only an inch long, and rarely as long as two
and a half inches. The primary pinnæ are either alternate or
opposite, — more frequently the former. The lowest ones are
considerably largest, and in the larger specimens are fairly bipinnate.
The secondary rachises, and, indeed, the upper part of the
primary rachis, are green and herbaceous ; as are also the segments,
which are narrowly oblong-linear, acute or mucronate at
the apex, having the edges recurved, and bearing a very delicate
erosely-toothed proper involucre. The segments, for this reason,
are somewhat pod-like. The veins are mostly simple, though
occasionally one is forked. They seem to be entirely free ;
although from Fig. i, a, of the illustration given by Brackenridge,
one would suppose they were reticulated.
Brackenridge’s specimens were very old, and somewhat shriveled
; and the anastomosing lines which his artist represented are
merely the depressions of a contracted surface. Sir W. J . Hooker
has noticed on the upper surface of the pinnules, when highly
magnified, “ an appearance of white, close-pressed, parallel hairs
lying in the direction of the margins, tapering at each end, like
the hairs of some malpighiaceous plant. A high magnifying
power shows that these are not separable from the cuticle, but are
rather lodged in it. Can they be looked upon as raphides?”
The cellules of the upper surface are oblong-linear, with
sinuous outlines, much as shown in the figure in “ Species F ilicum
; ” but I have failed to discover any thing in the least degree
resembling raphides.
The sterile fronds are very rarely found ; but, when they do
occur, their segments have serrated margins, — an uncommon
thing in this genus.
Plate XL , Fig. i. — Pellæa àensa. A plant of the natural size, showing
one frond contracted from drought, as is often the case, and one carefully
spread out, so as to display its true form. The smaller drawing shows
three fruiting segments enlarged.
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