142 



THE WOOD FERNS. 



also been described at different times 

 as a variety of both species. Present 

 day students, however, unite in con- 

 sidering it distinct. Nevertheless it is 

 a form to puzzle the novice, since it is 

 so easily confused with other species 

 that it often requires careful study to 

 separate them. In the cutting of the 

 fronds it is most like spinulosum ; in 

 shape it approaches cristatum. 



This species attains a height of from 

 two to three feet. The fronds are half 

 erect and oblong-lanceolate in outline. 

 The blade is about twice pinnate. In 

 the lower part, the pinnae are triangular- 

 ovate and again pinnate with oblong, 

 bluntish divisions, the largest of which 

 are cut into blunt segments with bristle- 

 like teeth at the apex. In the upper, 

 the pinnae are lanceolate, broadest at 

 base with broad, blunt-toothed seg- 

 ments. The frond is always twice pinnate be- 

 low, a point that makes its separation from the 

 crested fern easy. It is, however, somewhat 

 variable in its cutting and some forms are likely 

 to be often referred to spinulosum. 



The fertile fronds are much like the sterile 

 in shape though usually slightly taller and more 

 deeply cut. The sori are rather smaller than 

 those of cristatum and borne in a similar double 

 row on the pinnules. Nearly all specimens 

 have a tendency to produce one or more sori 

 on the teeth of the pinnules as well, thus obscur- 



Boottii. 



