SPINULOSE, OR COMMON WOOD-FERN. 



two roundish fibro-vascular bundles near the anterior side, 

 and three or four smaller ones near the back. 



The fronds always form a crown, and vary from three 

 or four to perhaps eight or ten from a single root-stock. 

 The root-stocks often branch, probably by the formation of 

 adventitious buds at the base of the stalks, and thus a single 

 plant may develop into a large cluster, sending up numerous 

 fronds of all sizes. 



The fronds of newly formed root-stocks, whether grown 

 from spores or derived from older plants by proliferous 

 development, are, of course, smaller than those of well-estab- 

 lished plants, but are generally also broader at the base, 

 being deltoid-ovate, while the fronds of older plants are either 

 narrowly or broadly ovate, but not deltoid, except in some 

 forms of var. dilatatum. 



Var. vulgare has fronds usually about twelve or fifteen 

 inches long, and four to seven inches broad in the middle, 

 the shape being oblong-ovate. The texture is firmly mem- 

 branaceous, and the color light-green, sometimes inclining to 

 yellowish-green. The pinnae diverge from the rachis at an 

 angle of from forty-five to sixty degrees. The lowest pinnae 

 are separated from the next pair by an interval of one and 

 a half to two inches, and are triangular-ovate in shape, the 

 pinnules on the lower side being twice as long as the corres- 

 ponding ones on the upper side, and the basal ones longest 

 of all. The second pair of pinnae are a trifle narrower and 

 commonly a little longer than the lowest, and the third pair 



