HYBRIDS OF ZEA RAMOSA AND ZEA TUNICATA 
By G. N. Collins, 
Botanist, Office of Acclimatization and Adaptation of Crop Plants , Bureau of Plant 
Industry, United States Department of Agriculture 
INTRODUCTION 
Data regarding the domestication of maize are still extremely meager. 
Yet a knowledge of this important agricultural step would be of such 
importance in tracing the early history of man and the beginnings of 
civilization that any investigations promising to throw light on the sub¬ 
ject need no further justification. 
The present study deals with the behavior of a hybrid between the two 
most striking variations or mutations from normal maize. Both have been 
considered as distinct species, Zea tunicata and Zea ramosa . Though 
usually referred to as agricultural species, they seem to deserve a place 
with the so-called species of Oenothera, which have originated through 
mutation. 
DESCRIPTION OF PARENTS 
Zea tunicata , or '‘pod com,” is a rather well-known variation of ordinary 
maize (Pi. 13,14,15). The most striking characteristic is that the glumes 
of the female inflorescence, or ear, are developed so that each seed is 
entirely inclosed. Associated with this character is a less conspicuous 
lengthening of the glumes of the staminate inflorescence that results in 
a thickening of the tassel (PI. 13, B). 
The origin of Z. tunicata is not known, but its occurrence in widely 
separated and isolated regions would indicate that it has originated 
independently more than once, presumably as a mutation from ordinary 
maize. So far as known, it has never appeared in pedigreed cultures, 
but there is at least one instance where it is reported to have appeared 
in a carefully bred commercial variety (Sconce, 1912). 1 
Z. tunicata is reported from Paraguay, Brazil, Argentina, Belgian 
Kongo, and many places in the United States. It was known to many 
tribes of American Indians. According to Parker (1910), both the 
Senecas and Mohawks had special names for tunicate maize, that in 
Seneca being translated as “original com.” 
Thus far we have found no definite reference to tunicate maize in 
Mexico, the reference given by Sturtevant (1894) being obviously a 
misidentification. Neither has it been reported from Peru, and in a most 
extensive vocabulary of the Quichua terms relating to maize obtained 
in Pern by Mr. O. F. Cook, of the Bureau of Plant Industry, who made 
1 Bibliographic citations in parentheses refer to “Literature cited/' p. 395. 
Journal of Agricultural Research 
Washington, D. C- 
ig 
( 383 ) 
Vol. IX, No. 11 
June 11,1917 
Key No. G 113 
