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Atkyrium alpestre, “ N y l a n d e r ; ” M i l d e , Fil. Eu. & Atl., p. 53.
Polypodium rhæticum, L in n æ u s , Sp. Pl., p. 1 5 5 2 , y f iA Schkuhr, 1. c. ; but
Moore thinks the plant not the same.
Aspidium rhæticum, S w a r t z , Syn. Fil., p. 59. — W il ld en ow , Sp. Pl., v.,
p. 2 8 0 .
H a b . — Among rocks at high elevations; on Lassen’s Peak, Mount
Shasta, Pyramid Peak, Mount Rose, and other high points in the Sierra
of California, B r ew e r , L emmo n , M u ir ; Cascade Mountains of British
Columbia, L y a l l . In the Alps and the mountains of Northern Europe ;
also in the Caucasus, and in Asia Minor.
D e s c r i p t i o n . — The root-stock is rather short, but branching,
and seems to form great entangled masses. The fronds
stand in a crown or circle, rising from the end of the root-
stock, which is made thick and heavy with the chaffy bases
of former stalks. Mr. Lemmon writes thus; “ It grows in a
limited locality, so far as I know, near the summit of Mount
Rose, near Webber Lake, and say at an elevation of 7,000 feet ;
lat. 39^° N. Fronds collected into a large mass four feet across,
short at the circumference, in the centre three feet high ; most of
them fertile, and densely so, as in the specimen sent.”
The stalks are usually but a few (four to six) inches long,
and in the dried specimens of a brownish straw-color, becoming
nearly black at the base. They bear a few large ferruginous
chaffy scales, and are deeply channelled and furrowed. The
fibro-vascular system of the stalk is altered by contraction in
drying, but apparently agrees with Dr. Milde’s description of
Athyrium : “ There are two oblong peripheric bundles in the
base of the stalk, which, at the base of the lamina, are united
into one of a horse-shoe shape by an arc parallel to the back of
the stalk." In the middle of a stalk from one of the California
specimens I find two systems of ducts, one on each side of the
stalk, and the two united by a curved and contorted border of
firm blackish tissue (sclerenchyma).
The fronds are from one to two feet long, and from three
to six inches wide. In general shape they are oblong-lanceolate,
acuminate, and slightly narrowed at the base. The texture is
softly membranaceous, and both surfaces are smooth. The
primary pinnæ are numerous, the lower ones gradually farther
apart : their shape is lanceolate from a broad base. They are
usually twice pinnatifid, the pinnules being connected by a very
narrow foliaceous border along the midribs. The ultimate segments
are sharply toothed. The fruit-dots are very abundant,
and usually are found on all the pinnæ. They are placed on
the back of the free veinlets, and are apparently devoid of indusium
; though Dr. Mettenius has discovered on young fronds an
exceedingly delicate and fugitive indusium, resembling in some
degree that of Asplenium § Athyrium. Accordingly, in his later
work, he referred the species to the genus Asplenium, placing it
next to A . Filix-fæmina. Milde, in his work on the ferns of
Europe and Atlantis, sought to re-establish Athyrium as a
genus, and placed this fern in it, saying “ sori . . . rotundi,
primum breviter oblongi indusio fugaci miiiutissimo ciliato
instruct!.” The spores are ovoid, and apparently covered with
anastomosing raised lines. Those I have examined are fuscous
brown, but Milde says “ sub-nigræ verrucosæ.”
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