269 



cles of Petalostemon, two of which are very similar in general 

 characters. These are P. candidiis and P. violaceus. They dif- 

 fer slightly in the size and number of their leaflets and in certain 

 minor characters, but the main distinguishing feature is in the 

 color of the flowers. In the first species these are white, and in 

 the second they are rose-purple. The two species can be, and 

 indeed are, recognized at a glance by their respective colors, but 

 assurance can be made doubly sure by an inspection of the 

 leaves. 



Another 



Impatiens 



native to our region. These are /. biflora and /. aurea. As in 

 the former case the color of the flower distinguishes the species. 

 In fulva it Is mottled red, and in pallida it is yellow. In the 

 leaves a slight dififerencc is noticeable, these being larger in one 

 than in the other, and In the position of the flower and the color 

 of the stem there is also a diflerence. But In spite of these, 

 which might here be called minor differences, the color Is the 

 main guide in separation. 



A third example is found in the two 



Melilotiis 



, M. alba, has white flowers, the other, M. officinalis, 

 has yellow ones. Here almost the sole distinction Is the color. 

 The shape of the leaves varies slightly, but the color of the flow- 

 ers comes first to separate the two species. 



Still another example of this point is observed In the two 

 species of Datura, namely, D. Stramonium and D. Tatula. In 

 the first of these species the flowers are white, and In the second 

 they are purple. The stem of the first is green and the second 

 purple, so that here not only does the color of the flower form a 

 characteristic feature, but that of the stem also. In other re- 

 spects they are almost precisely alike, so much so that Gray re- 

 marks that one is thought to be specifically distinct from the 

 other " on account of the behavior of the cross breeds." An or- 

 dinary student has not the time to inquire into the behavior of 

 cross breeds. In the meanwhile he takes the color of the flow- 

 ers as his distinguishing characteristic. 



The genus Baptisia is. In this relation, an interesting one. 

 There are five species In our district, and of the five only two are 



ahke in color. B. alba and leucantha are white ; B. kucoplma 



