[Illustration: ]
ADIANTUM PEDATUM, Linnæus.
American Maiden-hair.
Adiantum pedatum:—Root-stock creeping, scaly, and copiously rooting;
stalks scattered, a foot or more high, dark-brown and polished, forked at
the top; fronds six to fifteen inches broad, membranaceous, smooth,
spreading nearly horizontally, composed of several (six to fourteen)
slender divisions radiating from the outer side of the recurved branches
of the stalk, and bearing numerous oblong or triangular-oblong
short-stalked pinnules having the lower margin entire and often slightly
concave, the base parallel with the polished hairlike rachis, the upper
margin lobed or cleft and bearing a few oblong-lunate or transversely
linear reflexed involucres; sporangia on the inner surface of the
involucres (as in all _Adianta_), borne on the extended apices of the
free forking veinlets, which proceed from a principal vein closely
parallel to the lower margin of the pinnule.
_Adiantum pedatum_, Linnæus, Sp. Pl., p. 1557.—Thunberg, Flora Japonica,
p. 339.—Swartz, Syn. Fil., p. 121.—Schkuhr, Krypt. Gew., p. 107, t.
115.—Willdenow, Sp. Pl., v., p. 438.—Michaux, Fl. Bor. Am., ii., p.
263.—Pursh, Fl. Am. Sept., ii., p. 670.—Torrey, Fl. of N. Y., ii.,
p. 487.—Gray, Manual.—Ruprecht, Distrib. Crypt. Vasc., in Imp.
Ross., p. 49.—Hooker, Sp. Fil., ii., p. 28.—Brackenridge, Filices
of the U. S. Expl. Exped., p. 100.—Eaton, in Parry’s Exped. to
Japan, ii., p. 329.—Maximowicz, Primitiæ Fl. Amurensis, p.
341.—Mettenius, Fil. Hort. Lips., p. 47; Prolusio Fl. Japon. in
Ann. Mus. Bot. Lugd.-Batav., iii., p. 171.—Hooker & Baker, Syn.
Fil., p. 125.—Milde, Fil. Eur. et Atl., p. 31.—Keyserling, Gen.
Adiantum, in Mem. Acad. Petrop., ser. vii., xxii., No. 2, pp. 5,
28.
_Adiantum Americanum_, Cornutus, Canad. Pl. Hist., p. 7, t. 6 (1635).
_Maiden Hair, or Cappellus veneris verus_, Josselyn, New Englands
Rarities Discovered, p. 55 (1672).
_Adiantum fronde supra-decomposita bipartita_, _foliis partialibus
alternis_, _foliolis trapeziformibus obtusis_, Gronovius, Flora
Virginica (1739), p. 123. (For other ancient references see
Linnæus, as quoted above.)
_Adiantum boreale_, Presl, Tent. Pterid., p. 158.
Hab.—In rich, moist woods, especially among rocks. Common from New
Brunswick and Canada southward to Central Alabama, Professor Eugene A.
Smith, and westward to Lake Superior, Wisconsin, and Arkansas. Also in
Utah, California, Oregon, British Columbia, the islands of Alaska,
Kamtschatka, Japan, Mantchooria, and the Himalayan provinces of India.
Ruprecht speaks of specimens from Newfoundland, and Professor Gray
informs me that it exists in De La Pylaie’s collection from that
island.
Description.—The root-stock is elongated and creeping. It is about the
diameter of a goose-quill, is covered with minute ovate scales, roots
copiously from beneath and along the sides, and produces fronds from the
right and left sides alternately. The stalks are usually from a foot to
fifteen inches high, and from half a line to a line in thickness. When
very young, they bear a few scattered narrow scales; but these soon fall
off, leaving minute pointed scars. The mature stalk is roundish in
section, the convexity being greatest on the side which corresponds to
the under surface of the frond. The two convexities, anterior and
posterior, are separated by two obscure angles or ridges, which extend
the whole length of the stalk. The anterior, or flatter, convex surface
is nearly black, while the other side is a dark purplish brown. The
fibro-vascular bundle is U-shaped near the base of the stalk; but higher
up it is more like a broad, open V; and just below the forking of the
stalk it separates into two portions. The two branches of the stalk
diverge at an angle of about fifty degrees, and rise obliquely,
gracefully recurving till they nearly meet again. From the outer side of
the curve each branch sends out from two to seven slender diverging
branchlets, which are the rachises of the pinnæ. The branchlets nearest
the forking of the stalk are from four to fifteen inches long, those more
remote successively shorter. Thus the whole frond is from five or six to
fifteen or eighteen inches broad, and, while somewhat funnel-form in the
centre, radiates nearly horizontally towards the circumference. A pressed
specimen can give but little idea of its graceful position.
The pinnules, or leaflets, are from six to twelve lines long, and three
or four broad, and are placed alternately on the rachises of the pinnæ.
They are very numerous, seldom fewer than twelve on each side of one of
the middle (or lower) rachises, and in large fronds sometimes as many as
forty on each side. The outer rachises bear fewer and fewer pinnules, and
the outermost of even a very large frond will not have more than eight or
ten on each side. They are attached to the rachis by a very short and
slender stalk. Their usual form is dimidiate-oblong; that is, they appear
as if cut in two longitudinally, and the lower half removed, so that the
lower edge is entire, and straight, or often slightly hollowed; the base,
or edge nearest the rachis, is also straight and entire; it is parallel
with the rachis, or even overlaps it a little; the upper edge is more or
less lobed or incised, but in general nearly parallel with the lower, and
the end is rounded and slightly lobed. The point of attachment is, of
course, at the angle between the lower and basal edges. The terminal
pinnule of each pinna, and the basal one, which, indeed, very often
proceeds from one of the recurved branches _just below_ the origin of the
pinna, are broadly cuneate or transversely oblong in shape, the two sides
which meet at the point of attachment being equal; and the few pinnules
near the basal one are shorter and more triangular than the middle ones.
The texture is delicately membranaceous, but elastic; the color is a
lively green, and both surfaces are very smooth. The upper surface
appears to be destitute of stomata; and this may be the reason why water
will not adhere to the pinnules, but either falls off, or stands in
spheroids ready to fall. The veins are free: in the symmetrical basal and
apical pinnules the veinlets fork repeatedly from the very base; but in
the oblong middle pinnules there is a faint principal vein running close
to the lower edge; and from this the veinlets diverge obliquely, and fork
about three times before reaching the superior margin. The incisions of
the superior margin are usually very narrow, and extend only to about
one-third of the breadth of the pinnule; but in some specimens from
California and Oregon they are wider and considerably deeper. The lobes
are from four to six or seven in number: in sterile fronds they are
minutely toothed at the end; but in the commoner fertile fronds they are
reflexed and changed in character, so as to form somewhat crescent-shaped
or transversely elongated involucres of a pale-brownish color. The tips
of the veinlets extend into these involucres, and bear the sporangia on
the under or inner surface. In this peculiarity is the essential generic
character of _Adiantum_. The spores of this species are
spheroid-tetrahedral, the three radiating angles marked with slender
vittæ, or bands. They are mature in the latter part of summer; but the
fronds remain until frost, often changing from green to variegated shades
of brown.
There do not seem to be any well-marked variations in this fern. Ruprecht
has a “var. _Aleuticum_,” the _Ad. boreale_ of Presl, separated mainly on
account of its smaller size and fewer parts.
The genus _Adiantum_ contains eighty-three species, according to Mr.
Baker’s estimate; but this number is reduced to sixty-seven by the more
recent and very careful recension of Keyserling. The species vary in form
from a simple and reniform frond an inch or two in diameter to others
with ample tripinnate and even quadripinnate fronds. The species with
distinctly bipartite and radiated fronds are _Ad. patens_, _hispidulum_,
and _fiabellulatum_. _A. patens_ is found in Mexico and Central America.
It is a smaller plant than _A. pedatum_, and has deeply-sunken reniform
involucres. The other two occur in South-eastern Asia, the _hispidulum_
extending to Africa and to New Zealand, and the _flabellulatum_ to Japan:
the former has hispid surfaces and small roundish involucres; and the
latter has rusty-fibrillose rachises, coriaceous pinnules, and
transversely oblong sub-confluent involucres. _Ad. patens_ follows the
form and branching of our fern very closely; but the two Old-World
species often depart from it, and show a tendency to develop branches on
one or other of the longest pinnæ, thus indicating an approach towards a
pyramidal structure of the frond.
The remaining _Adianta_ of the United States are _Ad. Capillus-Veneris_
(Linnæus), found from North Carolina to California; _Ad. emarginatum_
(Hooker), which is the _Ad. Chilense_ of American botanists, but not of
Kaulfuss, found in California and Oregon; and _Ad. tricholepis_ (Fée),
which occurs in Texas and California, and extends southwards to Central
America.
The American Maiden-hair is easily cultivated, and will grow very freely
either in a shaded corner of a garden or in the house, and is perhaps
more elegant and graceful than any other of our ferns, the climbing-fern
scarcely excepted. Josselyn evidently mistook it for the Venus-hair, one
of the chief ingredients in a syrup which was formerly a famous remedy
for nearly all ailments, and said, “The Apothecaries for shame now will
substitute _Wall-Rue_ no more for Maiden Hair, since it grows in
abundance in _New-England_, from whence they may have good store.”
Mr. Emerton’s figure is taken from a living plant, and shows the frond
as it appears before it has been flattened in a collector’s portfolio.