B. P. I.— 799. 



A VARIETY OF MAIZE WITH SILKS MATURING 

 BEFORE THE TASSELS. 



INTRODUCTION. 



In the varieties of maize cultivated in the United States the anthers 

 usually open before the silks on the same plant appear, and pollen is 

 still falling when the silks are in a receptive condition. Except where 

 high and constant winds prevail at flowering time, this results in a 

 large proportion of self -pollinated seed. 



In maize self-pollination so reduces the vigor of the plants that any 

 means by which it can be avoided or reduced is worthy of careful 

 consideration. In nature wind-pollinated species, such as maize, 

 usually avoid self-pollination by producing pollen at a time when the 

 stigmas of the same plant are not in a condition to be pollinated. To 

 have the pollen produced before the stigmas are receptive (proteran- 

 dry) or the stigmas receptive before the pollen falls (proterogyny) 

 will prevent self-pollination. 



Of the two methods proterogyny would appear to be the more 

 advantageous, and is in fact more widespread, though Kerner's 

 statement x that "As far as we can tell at present all monoecious 

 plants are protogynous" has been materially modified. According to 

 Hackel, 2 proterandry is more general than proterogyny among the 

 grasses. Of the primitive varieties of maize from tropical America 

 that have been under observation in this country, nearly all are more 

 decidedly proterandrous than the improved varieties grown in the 

 United States. 



In spite of the fact that primitive varieties of maize are more often 

 proterandrous than improved varieties, there are reasons for believing 

 that the more remote ancestors of maize were proterogynous. 

 Whether teosinte (Evchlaena mexicana Schrad.), the nearest wild 

 relative of maize, is naturally proterandrous or proterogynous, seems 

 not to have been recorded. In our experiments one type of Euch- 

 laena secured from Durango, Mexico, was proterandrous to about 

 the same extent as the unimproved varieties of maize. Samples of 



i Kerner, A. J., and Oliver, F. W. Natural History of Plants, vol. 2, 1895, p. 313. 

 2 Hackel, E. " Gramineap," in Engler and Prantl, Naturliehen l'flanzenfamilien, Th. 2, Abt. 2, p. 2. 

 [Cir. 107 J 3 



