188 
Mutations and Evolution. 
south as Maine and Vermont, where type and variety sometimes 
occur together in the same colonies. 
The sunflowers of the middle Western States of America 
are a polymorphic group represented by great numbers of 
individuals. In 1910 a single mutant of Helianthus lenticularis with 
red instead of yellow rays was found at Boulder, Colorado by 
Cockerell (1912). It proved to be heterozygous and has since 
behaved as a simple Mendelian dominant in crosses with other 
species. In the history of its origin it forms an exact parallel to 
CEnothera rubricalyx. Cockerell (1915) has since studied many 
elementary forms in the wild species. He quotes from Church the 
history of the cultivated H. annuus, L. which is a gigantic non¬ 
branching form. Like maize, its origin in cultivation is only a 
matter of conjecture. Its seeds furnished the oil supply of pre- 
Columbian America, and apparently it is a product of Peruvian 
agriculture. It is very likely a gigantic form of some unknown 
species perhaps native of Mexico. Its cells should be examined, and 
their size compared with the cells of other species. Its relation to 
H. tuberosus, the girasole or Jerusalem artichoke, another Indian 
food plant, is also a matter of interest. In the latter species 
Cockerell (1919) has described a number of varieties, in cultivation 
and possible mutations in the shape of tuber, including 
mnltitubevculatus % fusiformis , purpurens and purpurellus. 
