16 BULLETIN 971, TJ. S. DEPAKTMENT OF AGEICULTUBE. , 



the irregular rows is another indicative characteristic. The shape of 

 these unbranched Fg ears and also of many of the Fg and F^ inter- 

 mediates strongly suggests the ears of a variety from the Canary 

 Islands, the tassels of which have been noted as suggesting Ramosa. 

 Other ears with 3 to 10 branches, similar to those found in Mr. Mack's 

 variety, resemble the branched-ear variation of the Pawnee variety 

 (PL XV) . A similar type of branching has been found in the Texas 

 Surcropper variety by Mr. W. W. Ballard and in the California 

 Yellow Flint by Mr. C. G. Marshall. However, in these forms of 

 branched ears from other than Eamosa stocks none has been found 

 that had more than 4 rows of seeds on the branches, while on many of 

 the Eamosa segregates the number of rows of spikelets on the basal 

 branches is frequently 8 and sometimes as many as 10 (PL XVI). 

 The gradation from typical ramose ears to ears without branches 

 affords evidence for the reduced-branched theory of the origin of 

 the many-rowed cob (2), although in many of the ears the rows are 

 extremely irregular and the abrupt taper from base to tip, with 

 the consequent continuous reduction in the number of rows, militates 

 against the development of the common cylindrical ear. Indeed, a 

 study of these ears raises a serious doubt as to the possibility of de- 

 veloping our present regular-rowed ears through a reduction of 

 lateral branches to pairs of spikelets. In many instances the inter- 

 mediate ramose ears clearly show that the branches reduce to a 

 single spikelet instead of a pair, and in consequence each alveolus has 

 but one seed; while the irregularity of the whole rachis precludes 

 the possibility of determining accurately the number of rows, it is 

 apparent that such ears could have an odd number of rows. The 

 origin of the original ramose variation in the Leaming variety is of 

 interest in this connection, since one of the most constant char- 

 acteristics of the Leaming variety is the poorly formed tip, which in 

 many ears appears to have been artificially joined to the main portion. 



It is difficult to visualize the common ear of maize as having arisen 

 through the reduction of the branches of the inflorescences as they 

 are now constituted, since there is little regularity in their present 

 arrangement. If the branches of a normal maize tassel were reduced 

 to paired spikelets, these spikelets would be arranged in a very 

 irregular manner on the rachis and would bear little resemblance to 

 the regular-rowed ears. If the reduction is assumed to have occurred 

 at an earlier period when the branches of the inflorescence had a dis- 

 tichous arrangement similar to the present arrangement of the vege- 

 tative branches, the resulting ear would have but four rows, and the 

 problem of their increase to the present number remains. 



Hackel has explained the increase in the number of rows as the result 

 of a coalescence of 4-rowed branches, a theory supported by numerous 

 bifurcated and bear's-foot ears. Collins (3), in studying teosinte- 



