362 Evolution and Adaptation 
on the former are twice as long as those on the short-styled 
form. The most important difference is found in the size of 
the pollen grains. These are larger in the long-styled form, 
being in the two cases in the proportion of 100 to 67, The 
shape of the grains is also different. Furthermore, the long- 
Fic. 5.— A, long-styled, and B, short-styled, forms of Primula veris. C, D, E, 
the three forms of the trimorphic flower of Lythrum salicaria, with petals 
and calyx removed on near side. (After Darwin.) 
styled form tends to flower before the other kind, but the 
short-styled form produces more seeds. The ovules in the 
long-styled form, even when unfertilized, are considerably 
larger than those of the short-styled, and this, Darwin sug- 
gests, may be connected with the fact that fewer seeds are 
produced, since there is less room for them. The important 
