SPINULOSE, OR COMMON WOOD-FERN. 



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 

 dilatatum 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. spinulosum, 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 



