BEAUTIFUL FERNS. 
25 
When the root-stock is erect, the stalk bases are loosely im- 
bricated 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 nearly 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. 
dilatatiim the scales have a very conspicuous dark central 
spot or stripe. This is sometimes lacking in European speci- 
mens, and generally so in North American. I notice a little 
of it in Oregon plants, and Milde speaks of the stalk of Ameri- 
can examples as being ^'paleis ferrugineis medio atris vestitus" 
In the typical A. spimdosum, which I follow Koch in naming 
var. vulgare, and in var. intermedium, the scales are concol- 
orous, either pale-ferruginous or fuscous-brown. The largest 
scales are 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 
