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mistaken for an Acrostichum. The indusia are mostly single;
but now and then a double, or diplazioid, indusium will be found.
They are very delicate, and have, as Schkuhr has well shown in
his figure, a beautifully ciliate margin. Spores ovoid-bean-shaped,
with a minutely-roughened surface.
This species need not be confounded with any other in North
America. Asplenhmi izioyitmium and A . septentrionale are the
nearest, and from both of these it is very easily distinguished.
There is in Europe a more closely related species, — A . Germani-
cum, — which may be known by the fewer, narrower, and decidedly
incurved segments, and especially by having the indusium entire,
and not ciliated. The wall-rue has been known to botanists for
three hundred and fifty years ; and in Heufler’s work on European
Asplenia there may be found many references to ante-Linnsean
descriptions of it, as well as a more abundant citation of later
references than I have thought necessary to give. See also
Moore’s Index Filicum and Milde’s European and Atlantic
Ferns.
Mr. Emerton’s illustration represents one of the commonest American
forms of this variable little fern.
P l a t e XV. —F ig . 2.
A S P L E N IU M S E P T E N T R IO N A L E , H o f f m a n n .
Fo rk ed Spleenwort.
A s p l e n i u .m SEPTENTRIONALE ; — Root-stocks short, creeping,
densely tufted, covered with narrow blackish chaff ; stalks
very slender, three to six inches high, dark-brown at the base,
green above, alternately forked, the branches gradually widening
into two to five very narrow cuneate and acuminate segments,
which are six to fifteen lines long, scarcely a line wide, and
incisely toothed at the apex; texture sub-coriaceous, and rather
rigid ; veins forked, closely parallel ; sori elongated, one to three
on a segment; indusia delicate, entire, or very sparingly ciliate.
H o f fm an n , Deutschlands Flora, ii., p. 1 2 .—
S w a r t z , in Schraders Journal, ii. (1800), p. 50; Syn. Fil., p. 75
— S c iik u h r , Krypt. Gew., p. 62, t. 6 5 .— W il ld en ow , Sp. PL,
p. 307. — P r e s l , Tent. Pterid., p. 106, t. 3, fig . 8. — M o o r e , Brit
Ferns, Nat. Print, t 4 1, C. — M e 'it e n iu s , iiber Asplenium, p. 14 1
— H o o k e r , Sp. Fil., iii., p. 17 4 ; Brit. Ferns, t. 26. — M il d e , Fil
Eur. et Atl., p. 81. — E aton, in B o t Mex. Boundary, p. 2 3 5.—
P o r t e r & C o u l t e r , Syn. FI. Colorado, p. 154.
Acrostichum septentrionale, L in næ u s , Sp. PL, p. 1524.
Pteris septentrionalis, S m ith , in Mem. Acad. Turin, v., p. 412.
Scolopendrium septentrionale, R oth , FI. Germ., iii., p. 49.
Acropteris septentrionalis, L in k , Hort. Berot, ii., p. 56 ; Eil. Sp. Hort. Berol.,
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