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an inch (Colorado p la n t s ) to nine inches (N ew York), or even
fourteen inches (M a d e ira ) . Similarly its width varies from
four lines to nearly six inches. But the usual size of fronds
in the Northern States is from six to eight inches long, and
two or two and a half wide. The fronds are so deeply pinnatifid
that the incisions extend almost to the rachis, and contiguous
segments are connected by only the narrowest wing.
The segments are usually oblong-linear from a more or less
dilated base; the lower ones but little if any shorter than the
middle ones, and the upper ones decreasing gradually, and so
passing into the incised or serrate and commonly acuminate
apex. The lower sinuses are broad and rounded, and the upper
ones narrower and more acute. The number of segments in
an ordinary frond is from fourteen to eighteen an each side.
Some very much dwarfed plants collected by Professor John
Wolf at an altitude of eleven thousand feet, near the Twin
Lakes of Colorado, have only four or five little roundish-oblong
lobes on each s id e ; and, to go to the other extreme, some
fine British fronds have as many as twenty-three lobes on each
side. The lobes are either obtuse or acute at the apex; and,
though the obtuse form is commoner here than in Europe,
neither condition is confined to either side of the ocean. The
margin of the segments -is also variable, being commonly obscurely
serrulate, often undulate, coarsely serrate (in specimens
from the south of Europe especially), or even again pinnatifid;
in which condition it has been found in several countries of
Europe, and at least twice in the United States. Fronds
with forked or variously distorted segments are l^y no means
uncommon.
Dr. Milde indicates ten varieties, — commune, attenuatimi,
rohmdatum, aizgustum, brevipes, aztritmn, serratum, occidentale,
Teneriffce, and Cambricztm. The first five differ merely by
longer or shorter obtuse or acute fronds and segments; the
sixth is an occasional monstrosity ; the seventh {serratum of
Willdenow) includes the large forms of Southern Europe, etc.,
having serrated segments ; the eighth {occidentale of Hooker)
is the plant of the Pacific coast, having acuminate segments ;
the ninth is a sub-glaucous form from Teneriffe and the
Azores; and the last (Cambricum) is an old Linnasan specific
name for a form, first found in Wales, in which the primary
segments are much widened, and pinnatifid into numerous
very narrow serrulate lobes. This variety is made to include
Moore’s var. semilacerznn, which differs principally in being
bipinnatifid only in the lower half, and often fertile; while
the original Cambriczmi is bipinnatifid throughout, and almost
always sterile. Var. Cambricum has been found near Stoning-
ton, Connecticut, by Miss Kate Stanton of that village, and at
Cold Spring, New York, by Miss Sarah P. Monks, at the time
a student in Vassar College. Professor Robinson finds in
Essex County, Massachusetts, various forms referrible to var.
aurituin.
The veins are all free, and the veinlets have thickened
apices. In the smaller fronds the veins are forked into two
nearly equal veinlets, of which the upper one may bear a sorus
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