BUTTERCUPS ; A STUDY OF SPECIES 



299 



FIG. 58. Corn butter- 

 cup (Ranunculus arven- 

 sis). Carpel with hooked 

 spines. 



one end of the series, near to the water- buttercups and 

 the spearworts, with which, however, it does not seem 

 to be very closely related. The goldilocks buttercup will 

 have to be placed close to the upright 

 buttercup, and this again must not be 

 widely separated from the creeping 

 and the bulbous buttercups. There is 

 a buttercup common in cornfields, 

 which differs from the rest in its carpels 

 and fruits, for they are few in num- 

 ber and covered with hooked spines. 

 Another buttercup (the hairy butter- 

 cup), whichis averyuncommon species, 

 has its carpels roughened by tubercles, 

 and the small-flowered buttercup has 

 rough carpels too. This, like the hairy 

 buttercup, is seldom met with. 



It is not difficult then to divide buttercups into such 

 as have smooth carpels, and such as have rough or spiny 

 carpels. Removing the buttercups 

 with rough carpels from the rest, we 

 have now left four species, which cannot 

 very well be denned by any positive 

 characters. There are some obvious 

 differences among them. For example, 

 in the golden and the upright butter- 

 cups the flower-stalk is not furrowed ; 

 in the creeping and bulbous butter- 

 cups it is. In the goldilocks buttercup, 

 as well as in the upright and creeping 

 species, the sepals spread horizontally, 

 whereas in the bulbous buttercup and in the three species 

 with rough carpels the sepals are reflexed, or bent down 

 when the flower is expanded. We can now apply these 

 distinctions to get a classification which complies with our 

 notions of affinity. Of the four buttercups in question 

 two (the goldilocks and the upright buttercup) have the 



FIG. 59. Petal of 

 water buttercup, with 

 exposed gland. 



