128 J our7ial of Agricultural Research voi. xvii, no. 3 



To avoid circumlocution it is necessary to consider as a morphological 

 unit the association represented by a sessile and pedicelled spikelet, as 

 they occur in the staminate inflorescence. It would be misleading to 

 refer to this unit as a pair of spikelets, because the same unit must also 

 be kept in mind in considering the pistillate inflorescence where one of 

 the spikelets may be suppressed. The two spikelets of a pair probably 

 arise from a single metamer, at least they seem never to become sepa- 

 rated. In the pistillate inflorescence, however, the individual metamers 

 can be distinguished with difficulty and the pairs of spikelets become so 

 profoundly and diversely modified that a general term is needed to 

 designate this structural unit in all its forms. 



In the pistillate inflorescence the members of this morphological unit, 

 whether it is represented by one or two spikelets, occupy a single 

 alveolus, and the complex might be described as the contents of an 

 alveolus. In the staminate inflorescence, however, the depression in 

 which the spikelets are borne is usually too slight to be termed an alveolus. 

 It seems desirable, therefore, to derive the general term from some word 

 that carries the same implication as alveolus but which has not been used 

 in a specific morphological sense. The word alicole ^ is proposed and will 

 be used in the following description to designate the spikelet or spikelets, 

 whether staminate or pistillate, that are borne in a single alveolus or at a 

 single point on the rachis, considered as the axil or point of attachment 

 of a reduced branch. 



The principal differences between the pistillate inflorescences of Zea 

 and Euchlaena may now be contrasted as follov.'s: 

 Euchlaena Zea 



Single spikelets Paired spikelets 



Two-ranked alicoles Many-ranked alicoles 



Separate alicoles Yoked alicoles 



SINGLE AND PAIRED SPIKELETS 



The difference between single and paired spikelets will be best under- 

 stood by considering first the arrangement of the spikelets in the stami- 

 nate inflorescence of Euchlaena, which is identical with that of the 

 lateral branches of the staminate inflorescence of maize. Since Euch- 

 laena lacks the specialized central spike of the maize tassel it may be 

 taken to represent the primitive arrangement of the spikelets. 



In these staminate inflorescences each alicole consists of two spikelets — 

 one sessile, the other pedicelled. The alicoles are disposed on the two 

 sides of the branch, leaving the lower, and, to a less extent, the upper side 

 of the branch, naked. The sessile spikelet is borne slightly below the 

 pedicelled, that is, toward the abaxial side of the branch. Thus when 

 viewed from the end of the branch the arrangement of the spikelets 

 would be such that instead of an alternation between pedicelled and 



1 Ala, armpit -t-co/t), inhabit. 



