abortion of one; (8) Sculpturing of the outer pistillate 
glume, rather than a lack of sculpturing; (4) Small ax- 
illary pulvini, instead of adnate prophylls. The last dis- 
tinction, the presence or absence of adnate prophylls, 
serves as a definitive character for separating the 4 ndro- 
pogoneae from the American Maydeae. The usual taxo- 
nomic separation involves the presence of perfect flowers 
in the former and unisexual ones in the latter. But this 
character in these and other tribes tends to be equivocal. 
Collins (1912) has pointed out the value of homozy- 
gous tunicate maize in demonstrating the close relation- 
ship of the American Maydeae to the Andropogoneae. 
Modern maize has been so modified by domestication, 
however, that we have turned to tunicate teosinte in order 
to determine if the series of compressions and reductions 
which occur in the Andropogoneae are an evolutionary 
extension of those which result in the cupulate fruit case 
in the Maydeae. The effect of the tunicate gene (7'u) of 
maize, when introduced by repeated backcrossing into 
teosinte, has been described by Mangelsdorf (1948). He 
states: ‘‘In tunicate teosinte the caryopsis is completely 
enclosed by prominent membranaceous glumes, and the 
rachis segment becomes nothing more than an appendage, 
playing no part in enclosing the caryopsis.”” More re- 
cently we have observed that the general structure of the 
fruit case in tunicate teosinte (or, more exactly, in half- 
tunicate teosinte) approximates a typical condition for 
the Andropogoneae. The resemblance is closest to the 
structure of Mlyonurus tripsacoides of the subtribe Rott- 
boellinae. In both cases the spikelets are borne in pairs 
along a slender, disarticulating rachis with slightly con- 
cave segments; the pedicellate spikelet is staminate (only 
in the distal portion of the tunicate teosinte spike), while 
the sessile spikelet is either perfect or pistillate; the floral 
bracts are long and herbaceous or unspecialized. The 
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