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9 ^ F E R N S OF NORTH AM E R IC A .
bundles, all of which are slender, are arranged in a circle
just beneath the surface of the stalk. Usually there is a
second imperfect circle, and in large stalks some rudiments
of a third, but the exact position of the inner bundles is
different in different stalks. I find no one large central bundle,
as observed by Mettenius.
Ihe pinnæ are sometimes as many as thirty on each
side, besides the terminal pinna, which is about as large as
those next to it, or even larger. More commonly there are
from fifteen to twenty pinnæ on each side, though sometimes
much fewer; and in one form, A . obliquum of Blume, the
fronds are simple and only a foot long. The pinnæ, even of
our Florida plants, vary in length from two inches to a foot,
and in width from half an inch to two inches. Some of the
smaller plants have elliptical pinnæ, the base equal and subacute,
and the apex rounded. Other plants have pinnæ linear-
strap-shaped, and over a foot long, the base rounded on the
lower side and cuneate on the upper, the apex obtuse but
mucronate. This is the A . incequale of Willdenow, which is
beautifully figured by Blume. The larger Florida plants have
the. base of the elongated pinnæ equally cuneate, and the
apex barely acute. A specimen from Tahiti has very broad
pinnæ with an acuminate apex. In some specimens, collected
in S. W. Florida by Dr. Garber, several of the pinnæ bear
a distinct auricle on the lower side, an inch or two above
the base. This auricle is from one to five inches long, and
has a special midvein. One pinna has two such auricles,
side by side.
F E R N S O F NO R TH AM E R IC A . 97
In the living fern the pinnæ have their edges more or
less undulate, a character which may often be seen also in
herbarium specimens. The pinnæ have an almost coriaceous
texture; the upper surface is dark green and shining; the
lower surface paler and usually smooth, but hairy in a form
found in Brazil, the Cape of Good Hope, etc. The midnerve
is strong, and prominent beneath. The veinlets are
copious, and anastomose in very fine obliquely-placed oblong
or oblong-hexagonal areoles. The very edge of the pinnæ
is translucent and somewhat thickened, and is often slightly
recurved. The surface cells are irregularly star-shaped, with
rounded interlocking points. In the lower surface there
are numerous stomata, much like those of common flowering-
plants. Fée comments on the presence of these stomata, and
seems to consider them a rarity among Ferns. But they
exist, though perhaps less abundantly, in Onodea sensibilis,
Woodwardia angttslifolia, Aspidium Filix-mas, Polypodium
vulgare, etc., etc., and not improbably in all Ferns. '
The sporangia are produced in great masses entirely covering
the under surface of the pinnæ. Dr. Garber states '
that, in plants near the seacoast of Florida, a few of the
fronds are taller than the others, and have all the pinnæ fertile
and closely appressed to the rachis; but that in a form
frequently seen on the Corkscrew river, the fronds are only
two or three feet high, the pinnæ few, distant on the rachis,
and all the fronds with from one to five of the highest
I. See Sachs’s Text-Book, Engl, version, p. 88.
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