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. 
