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' ‘ ^ FERNS OF NORTH AMERICA.
p. 80. — F é e , Gen. F il., p. 77, t. é, A. — H e ü f le r , Aspl., Sp. Eur.,
P- 344-
Amesium scptaitrimiak, N ew m an , Hist. Brit. Ferns, ed. iii., p. 265.
H a s . — On Ben Moore, New Mexico, B ig e low , W r ig h t . Colorado,
H a l l & H a r b o u r ; and growing with Asplenium Trichomanes along the
brink of the Grand Canon of the Arkansas, B r .a n d eg e e . It is found in
crevices of rocks and on walls in Great Britain and in the mountainous
regions of Europe, and in Asia as far as Cashmere and Kiimaon.
D e s c r i p t i o n . — The habit of growth is very much as in the
wall-rue, except that this species forms still more extended tufts,
rhc scales of the root-stock are very similar to those of the species
just named, but bear a few pedicelled marginal glands. The
stalks are commonly longer than in the other species ; and, after
tlie upper greenish portion has broken away, the lower or dark-
brown part persists a long time. The section of the upper part
of the stalk shows that it has three longitudinal furrows, though
two of these may be due to drying. The fibro-vascular bundle is
oval in section, and the central or more truly vascular portion
of it is triangular with hollowed sides. The stalk is either
forked or alternately branched at the top, and bears from two to
five very narrow segments. These taper both at the base and
apex: they are sometimes forked, but more frequently toothed
and incised towards the apex. The veins are forked near the
base of the segment into as many closely parallel veinlets as there
are teeth to the segment. The sori are often nearly an inch long
and, when the sporangia are ripe, nearly cover the back of the
segment. The indusia open towards the median line of the segy
FERNS OF NORTH AMERICA. >13
ment, and are so broad as to sometimes overlap each other. They
are composed of cellules with very sinuous borders, and have a
usually entire edge, though here and there a few short marginal
hairs may be detected, — a point which seems to have escaped the
close and usually accurate observation of Milde. The spores are
ovoid-bean-shaped, and minutely roughened. It is a somewhat
remarkable thing in the geographical distribution of ferns, that
this curious little fern should be by no means uncommon in the
mountainous regions of Europe and of Western and Southern
Asia, and should occur in America, not in those parts of the continent
nearest to Europe, nor in the more northern regions, but in
what may be called the very heart of the continent. I believe Dr.
J . M. Bigelow was the first to detect it, in 1851 ; though it may
have been collected by Mr. Charles Wright a little earlier.
A glance at the synonymy will show the very great diversity
of views which authors have formerly held as to its generic affinities
; but the more recent writers on the subject, with scarcely
an exception, have considered it an Asplenium. Mr. Newman, •
who proposed to erect the genus Amesium for this plant and for
A . Ruta-fmtraria and A . Germanictmi, was disposed to doubt
whether all the three might not be so connected together by
intermediate forms as to constitute but one really good species.
Mr. Emerton has taken his illustration from a plant, with five fronds,
collected by Mr. Brandegee in Colorado. One segment is shown, some-
what magnified.
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