36 IOWA ACADEMY OF SCIENCE 



similar results. W. J. Beal/ A. J, Cook,^ F. A. Sirrine,^ and Kirchner^" 

 found that red clover is not self-fertile. Robertson^^ discussed the pol- 

 lination of clover by insects. Prof. Hunt^" states: "It has long been 

 recognized that red clover and other leguminous flowers may be self- 

 pollinated, although it has never been determined whether self-pollina- 

 tion, or cross pollination most commonly occurs." The same writer^^ 

 states also, "The organization of the flowers of the legumes is such 

 that cross-pollination can occur only by means of insects or other ex- 

 ternal agencies. That pollen in some species and perhaps in all species 

 may pollinate the stigma of its own flower seems certain. That the 

 showy flowers common to legumes serve to attract insects which visit 

 them for nectar and pollen, and thus to bring about cross-pollination 

 seems equally certain. Whether self-fertilization or cross-fertilization 

 most commonly occurs is a matter requiring further investigation." 



PammeP* states, "It is generally supposed that the second crop of 

 clover produces more seed than the first. This, I think, is due to in- 

 sects, there being a much larger crop of bumble-bees at the time of the 

 second flowering, than at the first." 



To these observations might be added the experience of clover grow- 

 ers in New Zealand. Dunning^ ^ gives an account of the introduction of 

 bumble-bees into Australia. Previous to the introduction of these in- 

 sects no clover seed was produced, but when they began to spread, and 

 became a part of the insect fauna, the red clover also began to spread 

 rapidly. The inference may be drawn that the bumble bee had some- 

 thing to do with seed production of the plant in Australia. 



Structure of the Flower. 



The flowers of red clover are produced in heads. The number of 

 heads per stalk varies from 1-14 heads. The number of flowers is ex- 

 tremely variable. The average, however, as shown by Miss Edna C. 

 Pammel for Ames, is, for black loam first crop 71.1; for black loam 



^Grasses of N. Amer. i: 235-238. 



*Cook, A. J. Bull. Difv. Ent. 26:87. 



»Sirrine, F. A. Bull. la. Agrl. Exp. Sta. 13:89. 



'°Kirchner. Ueber die Wirkung der Selbtbestaubung bei den Papilionaceen. 

 Naturwissenschaftliche Zeitschrift fur Land. u. Forst Wissenschaft. 3:1-16, 

 49-64, 97-111. 



"Bot. Gaz. 17:177. 



"Wallace's Farmer. Oct. 22, 1909. 



"Forage and Fiber Crops in America. 124. 



"Henry Wallace. Clover Culture. 121-123. 



'=^Proc. Entomological Soc. London. 1886. 



