GENERA OF GRASSES OF THE UNITED STATES. 
287 
races of American aborigines, from Peru to middle North America. 
Several races of corn are grown in the United States, 1 the most im- 
portant being dent, the common commercial field sort, flint, sweet, and 
pop. Pod corn (Z. mays tunicata Larr.), occasionally cultivated as a 
curiosity, is a variety in which each kernel is enveloped in the 
elongate floral bracts. A variety with variegated leaves (Z. mays 
japonica Korn.) is cultivated for ornament. 
144. Coix L. 
Spikelets unisexual; staminate spikelets 2-flowered, in twos or 
threes on the continuous rachis, the normal group consisting of a pair 
of sessile spikelets with 
a single pedicellate 
spikelet between, the lat- 
ter sometimes reduced 
to a pedicel or wanting ; 
glumes membranaceous, 
obscurely nerved; 
lemma hyaline, nearly 
as long as the glumes, 
awnless, 5-nerved ; palea 
hyaline, a little shorter 
than the lemma; sta- 
mens 3; pistillate spike- 
lets 3 together, 1 fertile 
and 2 sterile at the base 
of the inflorescence ; fer- 
tile spikelet consisting 
of 2 glumes, 1 sterile 
lemma, a fertile lemma, 
and a palea ; glumes sev- 
eral-nerved, hyaline be- 
low chartaceous in the 
upper narrow pointed fig. m 
part, the first very 
broad, infolding the spikelet, the margins infolded beyond the 2 
lateral stronger pair of nerves, the second glume narrower than the 
first, keeled; sterile lemma about as long as the second glume, similar 
in shape but a little narrower, hyaline below, somewhat chartaceous 
above; fertile lemma hyaline, narrow, somewhat shorter than the 
sterile lemma ; palea hyaline ; narrow, shorter than the lemma ; sterile 
spikelets consisting of a single narrow tubular glume as long as the 
fertile spikelet, somewhat chartaceous. 
Job's-tears, Coix lachryma-jobi. Upper por- 
tion of plant, X 1. 
1 See Montgomery, The Corn Crops, 15, 1913 : Sturtevant, U. S. Dept. Agr., Off. Exp. 
Sta. Bull. 57. 1899. 
