4 MAIZE WITH SILKS MATURING BEFORE THE TASSELS. 



Euclilaena seed from Florida, Costa Rica, and one of unknown origin 

 imported from London produced plants that were all proterogynous. 

 The season was too short, however, for any but the Durango plants 

 to mature seed, and the unusual conditions may have caused the 

 plants to behave abnormally. 



It is known that hybrids between maize and teosinte are common 

 in the region about Durango. In fact, seeds that were obviously 

 hybrids between the two species were found in the lot from which our 

 plants were grown. It is therefore possible that although the plants 

 showed nearly all the characters peculiar to Euclilaena, except that 

 they were less branched, they may still be very dilute hybrids with 

 maize, thus accounting for their proterandrous habit. The pro- 

 terandrous habit in the Durango variety of teosinte is evidently asso- 

 ciated with the development of a well-defined mam stalk, or culm, 

 a character which it shares with maize and by which it differs from 

 the other types of teosinte. 



Aside from the question whether teosinte is naturally proterogy- 

 nous or not, there is evidence for the belief that the proterandrous 

 habit of maize is the result of the separation of the sexes into different 

 parts of the plant and that the perfect-flowered ancestors of maize 

 were proterogynous. 



It is a very common occurrence in maize for pistillate flowers to 

 be developed in the staminate inflorescence as perfect flowers or 

 as scattered pistillate spikelets, or, more often still, for a portion of 

 the inflorescences to be completely pistillate. An example of the 

 frequency with which pistillate flowers occur in the terminal inflores- 

 cence of suckers may be seen in the classification of suckers given 

 on page 10. Another abnormality in maize of even more frequent 

 occurrence than pistillate flowers in the staminate inflorescence is 

 for the pistillate inflorescence, or ear, to terminate in a staminate 

 spike. 



Whenever male and female flowers occur in the same inflores- 

 cence of a maize plant as a result of either of these common abnor- 

 malities it has always been observed that the silks are developed 

 some days before the male flowers open. If these abnormalities are 

 looked upon as reversions to a perfect-flowered ancestor it seems 

 reasonable to assume that this primitive ancestor was proterogynous. 



ADVANTAGES OF PEOTEROGYNY. 



Selection for earliness and the crusade against the so-called barren 

 stalks have without doubt operated to change the condition of pro- 

 terandry that obtains in the unimproved varieties of maize to one of 

 approximate synacme, where pollen and silks appear simultaneously. 

 Synacme is certainly less desirable than proterandry, but now that 



[Cir. 107] 



