BIRTHWORT FAMILY 159 



from a root compels cross-fertilizing between 

 flowers of distinct plants to insure the most vig- 

 orous seed, as Darwin proved. After fertiliza- 

 tion, the cup nods, inverted, and the leathery 

 capsule following after it, bursts irregularly, scat- 

 tering many seeds." 



The typical form of the Wild Ginger is widely 

 distributed in eastern America. Two other 

 species have recently been separated from it. One 

 is the Long-tipped Wild Ginger in which the 

 calyx-lobes are long and slender; the other is 

 the Short-lobed Wild Ginger in which the calyx- 

 lobes are short and triangular. Both of these 

 species are widely distributed as far west as Iowa. 



