logical wild maize ears and the present-day correlation 
between ear size and pollen grain size are indicative 
(Galinat, 1961). Our data (Table II and Plate XLVIT) 
on the variation in pollen size of three species of Tripsa- 
cum, show that Tripsacum pollen is, on the average, 
larger than that of Manisuris, but not substantially so. 
This might be expected, if the wild maize parent of 
Tripsacum had pollen about the size of modern teosinte 
or slightly smaller, since the ranges of size variation of 
Tripsacum and teosinte do presently overlap. 
The first 4 or 5 mm. of style length immediately above 
the pistil in Tripsacum are fused, a feature usually not 
observed because it is usually concealed by the outer 
glume. This partial fusion may be an expression of germ- 
plasm from maize since this grass is unusual in having its 
styles (actually stigmatic branches) fused for almost their 
entire length. In Manisuris, the bifurcation of styles is 
complete. The styles of Manisuris also have numerous 
long hairs presenting a feather-like appearance, while 
those of maize usually have sparse hairs; and here, too, 
Tripsacum is intermediate though extremely variable. 
The cupulate fruit case of Tripsacum, a device which 
protects the grain by means of a complicated relation- 
ship between spikelet and rachis segment, appears at first 
to be a sudden development in an otherwise gradual 
trend in the tribe Andropogoneae leading towards its 
formation (Galinat, 1956). Its structure may be the re- 
sult of an elaboration upon a combination of features 
coming in from both putative parents. From maize came 
the unique and essential feature of the cupule, a corneous 
cavity with wide lateral wings that develops in the rachis 
immediately above the attachment point of the pistillate 
spikelets. The specialization of the cupule in ‘Tripsacum 
as a functional part of the fruit case may have occurred 
sometime after the origin of this species. Since the wild 
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