2901] 



CHA MBERLA IN—BOTR YCHIUM 



395 



deeply cut that the bipinnate condition is reached. We do not 

 regard Botrychium as a similar case, but believe that the differences 

 in the margins of B. obliquum and B. dissectum are more like the 

 differences in the margins of the leaflets of Boivenia spectabilis 

 and B. scrrulata, and like the differences in the leaf margins of 

 Dloon edule and D. spinulosum. In these four cycads, the margins 

 are so constant that they are reliable diagnostic characters. 



The short subterranean stem, with the long-stalked leaf 

 and spore-bearing portion with a still longer stalk, is similar in 

 B. obliquum and B. dissectum. 



The roots of B. dissectum are wrinkled and fleshy, like those of 

 B. obliquum, and not at all like the slender roots figured in Britton 

 and Brown's Illustrated Flora. 



In general, B. obliquum is a larger plant than B. dissectum. 

 At Oberlin the largest plant of B. obliquum measured 35 cm. in 

 height, with a leaf 20 cm. in width, 

 and the spore-bearing part of the 

 fertile spike 15 cm. long. While this 

 is not quite up to the limit in size 

 recorded for the species, it is very 

 large, and most individuals are much 

 smaller. One plant of B. dissectum 

 measured 28 cm. in height, but this 

 is exceptional. The usual size of 

 B. dissectum is about two-thirds that 

 of B. obliquum. 



The most suggestive difference 

 between B. obliquum and B. dis- 

 sectum is seen in the fertile spike. The sporangia of B. dissectum 

 sometimes look uniform and perfect, but somewhat smaller than 

 those of B. obliquum. The difference in size, where the sporangia 

 seem to be perfect, may be seen by comparing A and D of 



fig. 9- 



However, most specimens show a considerable proportion of 

 abortive sporangia which, even without sectioning, may be dis- 

 tinguished by their smaller size (fig. 9, B and C). The figure of 

 B. dissectum in Britton and Brown's Illustrated Flora is evidently 



Fig. 8. — Leaflets from three 

 plants of B. dissectum; natural size. 



