HERITABLE CHARACTERS OF MAIZE 



XIV — Branched Ears 



J. H. Kempton 

 Bureau Plant Industry 



THE number of simple ]\Iendelian 

 characters reported for maize is 

 increasing" constantly and creat- 

 ing the erroneous impression that all 

 heritable teratological variations result 

 from changes in single hereditary 

 units. Following the discovery of a 

 new abnormality the customary pro- 

 cedure is to inbreed for several genera- 

 tions, propagating only those individ- 

 uals which express the character in its 

 most extreme form. After this treat- 

 ment abnormalities which fail to be- 

 have as simple or comparatively simple 

 characters when crossed with closely 

 related normal individuals must bide 

 their time until the mode of inheritance 

 of the more simple characters has been 

 determined satisfactorily. This pro- 

 cedure is quite logical and fully justi- 

 fied by the results, although it can 

 but lead the reader unversed in genetic 

 practice to believe that the inheritance 

 of the majority of the most striking 

 characters is quite simple. 



The present paper deals with a char- 

 acter fully as striking as most of its 

 predecessors in this series but dififering 

 from them in the mode of inheritance. 

 This character is manifested by the 

 production of seed-bearing branches at 

 the base of the ear and clearly repre- 

 sents a reversion to a less specialized 

 form. It is well known that the 

 terminal panicles of tillers or suckers 

 commonly bear pistillate as well as 

 staminate spikelets and that all degrees 

 of the production of seeds in these in- 

 florescences exist, ranging from normal 

 branched staminate panicles to inflor- 

 escences completely resembling ears, 

 having no branches and producing 

 nothing but pistillate spikelets on fully 



developed cobs. So varied are the in- 

 florescences of suckers that in order to 

 classify the different sorts we have es- 

 tablished sixty types which represent 

 fairly well the stages from the normal 

 branched staminate inflorescences to 

 unbranched ears. The suckers borne 

 on diiferent plants range in type from 

 something resembling an upper floral 

 branch or ear to a replica of the main 

 stalk. The variations in the type of 

 inflorescence clearly result from the at- 

 tempt to adjust a bisexual inflorescence 

 on a monoecious plant which normally 

 has the sexes in separate inflorescences. 

 In view of the unstable condition 

 prevailing in the character of the in- 

 florescences of suckers it seems note- 

 worthy that the character of the ear 

 should remain so constant though sep- 

 arated from the suckers by but a few 

 metamers and related to them through 

 an unbroken series of buds. In all 

 maize plants there is a section of sev- 

 eral metamers with dormant buds 

 which separates the pistillate branches 

 or ears from the vegetative branches 

 or suckers and presumably it is in this 

 transitional section that the character 

 of the inflorescence becomes stabilized 

 in an unbranched pistillate form. 



Types of Branched Ears 



Five forms of branched ears are 

 recognized, of which bearsfoot and 

 ramose are the most common, these 

 having formed the basis of theories of 

 the origin of the ear. They are shown 

 in Figures 1, 2 and 3. 



A third form in which two or more 

 entire and otherwise normal ears are 

 united in a single inflorescence was 

 found by Collins and Doyle at Tuxtla, 



243 



