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This plant is usually considered the type of the species ;
it is very common in Europe, less so in America," It is well
represented on Plate xxi of Moore’s Nature Printed British
Ferns, and on Plate 18 of Hooker's British Ferns. Being
obliged to give it some distinctive name as a variety, I have
selected what seems to be the oldest, that used by Koch,
who, however, placed the species in Polystichum.
Var. intermedium has fronds a little broader in outline
than those of var. vulgäre, and often larger; measuring not
unfrequently twenty-two inches long and nine inches broad
The color is dark-green. The pinnæ diverge from the rachis
at an angle of from sixty to ninety degrees, being usually
more spreading than in the type of the species. The lowest
ones are sometimes nearly three inches distant from the next ;
they are triangular-ovate in outline, and have the pinnules of
the lower side much longer than those on the upper side.
The first or basal pinnule is generally a little shorter than
the second one, a point noticed by Milde, but apparently
hitherto overlooked by American authors. Successive pinnæ
are a little narrower and longer, the longest ones being commonly
those just below the middle of the frond. The
secondary rachises are very narrowly winged. The pinnæ are
usually fairly bipinnatifid, being one degree more compound
I Milde has as sub-varictics, exaltatum, with dark-grccn glabrous fronds, elevatum,
with narrower yellowish-green and somewhat glandular fronds, and Amurense, with
broadly ovate fronds chaffy beneath with little búllate scales. He says that towards the
north o f Europe the true spinulosum becomes scarce and passes gradually into var.
dilatatum.
than in var. vulgare, though there are fronds in which they
are only once pinnatifid. The secondary pinnæ are usually
distinctly stalked, and are spreading like the primary ones.
The tertiary pinnæ, or segments, are oblong-ovate, obtuse, and
spinulosely toothed on the sides and at the apex. The under
surface of the rachises and pinnules are minutely glandular
with unicellular cylindrical or capitate glands. The venation
is the same as in var. vulgare, and I see no difference in
the position of the sori, which are dorsal if on the veins, or
either dorsal or sub-apical if they are formed on branches of
the veins. The indusium is sprinkled on the surface and at
the margin with stalked and sessile glands.
Mr. Davenport has endeavored to elevate this variety to
the rank of a species, under the name of Aspidium Ame ricanum,
rejecting the name of intermedium because Willdenow’s
description “ does not contain a word in regard to the glandular
indusiums and under surface, while, on the other hand,
his description of A . spinulosum does, thus exactly reversing
the usual arrangement.” To the first objection it may be
replied that neither does Willdenow speak of the glandular
lower surface and indusia of A . rigidum, where the glands
are much more conspicuous ; to the second that A . spinulosum
is often glandular in European specimens. Willdenow had
no American examples of the true spinulosum. Milde, who
had examined the specimens of intermedium sent by Muhlenberg
to Willdenow, says it is “ nothing but a common form of
A . spinulosum!' But our intermedium he refers to his
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