ABSTRACT 
Pollen of the Gramineae are spheroidal in shape and 
monoporate. The pore is surrounded by a thickened 
area, the annulus. Size characteristics, both of total pol- 
len diameter and the relation of this diameter to the pore 
width have been used in the past to separate the pollen 
of maize from teosinte and T'ripsacum. Use of measure- 
ment alone causes several difficulties, the most important 
being that large numbers of grains are necessary for posi- 
tive identification. Morphological characteristics of the 
exine, studied under phase-contrast light, give more con- 
clusive discrimination even when dealing with few grains. 
Maize and teosinte can easily be separated from Tripsa- 
cum. Primitive maize and primitive teosinte can also be 
separated, When dealing with hybrid races of maize of 
teosinte, discrimination appears to depend largely on 
how much germ plasm each plant has absorbed from the 
other. Thus, the pollen of teosinte Chalco, that grows 
commoenly around maize fields in Mexico and frequently 
crosses with maize, is very difficult to tell from that of 
a very tripsacoid maize like Huesillo. That this pollen 
morphology is genetically controlled is supported by 
observations on pollen of derivatives of maize-teosinte 
hybrids. Suggestions for dealing with apparent maize 
pollen in the archaeological record are made. 
