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166 F E R N S O F NORTH AM E R IC A .
275.—L a s t rea - d i la t a t a . P r e s l , Tent. Pterid., p. 77.—M o o r e , Nat. Pr,
Brit. Ferns, t. xxii—xxvi.—D r y o p t e r i s d ila ta t a , G r a y , Manual, ed. ¡., p.
5 3 1 .— A s p id iu m c am p y lo p te rum , K u n z e , in Silliman’s Journal, July,
1848, p. 84.
H .a b .— In shady woods, often in springy places and along shaded
rivulets, from Newfoundland to Oregon and North-West America, and
extending southward to North Carolina, Tennessee and Arkansas. The
typical form, our var. v u lg a r e , ha.s been seen in Newfoundland, New
Brunswick, Canada, New England, the Middle States, Kentucky, about
Lake Superior, and westward to British Columbia. Var. in t e rm e d ium
has nearly the same range, but extends to Tennessee and probably to
Arkansas, and is not reported from Newfoundland. It is the common
form of the species in the northern United States. Var. d ila ta t um is
found on the higher mountains of New England, and extends along
the Appalachian chain to North Carolina: it is known in Newfoundland,
New Brunswick, Canada, and thence westward to Oregon, British Columbia
and Alaska. In New England and New York it seems to pass
in less mountainous districts into both the other forms. A s p id iu m
s p in u lo s um , in several forms, is common in Europe and northern Asia,
and is credited to the Cape of Good Hope also. Var.
seems to be exclusively North American.
D e s c r ip t io n ; — The root-stock is either creeping or assurgent,
or even occasionally erect. It may sometimes be
found s ix or eight inches long, but is usually much shorter.
It has an actual diameter of about a quarter of an inch, but as
the fleshy bases of the stalk are adherent and continuous with
it, and persist unwithered for at least a year after the fronds
have gone, the thickness of the whole is considerably greater.
A
F E R N S OF NO R TH AM E R IC A . 167
When the root-stock is erect, the stalk bases are loosely imbricated
on all sides of it, but when it is assurgent or
creeping, the stalk-bases of the lower side are curved upwards
towards the light. The root-stock consists mainly of greenish
parenchymatous cells filled with starch. The fibro-vascular
bundles are very slender, few in number, and placed in an
irregular circle.
The stalks are from a span to sometimes neatly two
feet long, rather slender, rounded at the back, channelled
in front, and lightly furrowed along the sides. They are
dark-fuscous at the base, but above the base are greenish,
or slightly brownish along the back. When young they are
very chaffy, especially near the base, but the chaff gradually
wears away, and at length very little of it remains. The
character of the chaff varies in different specimens, and to
some extent in the varieties. In European examples of var.
dilatatum the scales have a very conspicuous dark central
spot or stripe. This is sometimes lacking in European specimens,
and generally so in North American. I notice a little
of it in Oregon plants, and Milde speaks of the stalk of American
examples as being "paleis ferrziginds medio atris vestitust’
In the typical A . spimdosmn, which I follow Koch in naming
var. vulgare, and in var. intermedium, the scales are concol-
oroiis, either pale-ferruginous or fuscous-brown. The largest
scales arc seldom more than half an inch long. They are
ovate, acuminate, entire, and composed of narrow linear
slightly sinuous cellules. The section of the stalk discloses
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