T1ÙS is ratlier a diminutive plant, but, when in a vigorous
state, has a very interesting appearance, from the contrast
between its black stipes and rachis, and the bright green
pinnæ, and from the regularity with which the latter are
disposed. It grows in tufts, naturally introducing itself
into the joints of old masonry and among the crevices of
rocks, and producing numerous small slender fronds, of a
linear form, in its most vigorous state nearly a foot long,
but generally from three to six inches. They are evergreen,
simply pinnate, on a rather short stipes, which is of a
purplish-black, the rachis also being of the same dark
colour. The pinnæ are dull green, small and numerous,
equal-sized, of a roundish-oblong figure, attached to the
rachis by a stalk-like projection of their posterior base;
the margin is rather entire or crenated. The pinnæ are
jointed to the rachis, and when old are readily displaced, so
that eventually the black rachis is left denuded among the
tuft of fronds.
A distinct midvein passes through each pinna, giving off
on each side a series of venules hearing veinlets, the anterior
of these producing the linear sorus just within the
margin of the pinnæ. The sori, which in the young state
are covered by a thin indusium having a somewhat creuu-
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