COMPARATIVE ANATOMY 



89 



it can be recognized.) But we have other plants whose 

 blossoms in their form so closely resemble those of the 

 common Viola cucullata, and which in their whole appear- 

 ance are so similar, that we conclude they are connected 

 with this species; yet the differences are sufficiently great 

 for us to be unable to assign them to this species. One 

 kind of these violets have 

 smaller blossoms with a 

 much longer spur. Their 

 stems are highly developed 

 and branching, while their 

 leaves are smaller and are 

 borne upon shorter petioles 

 (Fig. 12). These we classify 

 as Viola rostrata, indicating 

 the difference between the 

 two types by the different 

 specific names, but at the 

 same time calling attention 

 to the resemblance between 

 the two forms by giving 

 them both the same genus 

 name, Viola. There are 

 a dozen or more species of the genus Viola found around 

 Baltimore. In this same region is found an apparently 

 very different plant with tall and branching stems, with 

 coarse leaves and small greenish blossoms, a coarse, weed- 

 like plant (Fig. 13). This form has been named Solea 

 concolor. Now, great as are the superficial differences be- 

 tween this species and our violets, careful study shows that 

 the blossoms of both are made up on the same plan, and 



FlG. 12. Viola rostrata. From Britton and 

 Brown's Illustrated Flora of the Northern States 

 and Canada, by the courtesy of the authors and 

 of Charles Scribner's Sons. 



