GENEKA OF GRASSES OF THE UNITED STATES. 283 



described species from Mexico is a perennial with simple culms and 

 creeping rhizomes. A form which is supposed to be the original 

 E. mexicana is cultivated occasionally in our Southern States, where 

 it is known as teosinte (fig. 171). This is a tall, stout grass, usually 

 branching at the base and forming large clumps. The tassel is like 

 that of corn, and the fascicles of spikes, inclosed in husks with the 

 long styles or silk hanging from the apex, bear a superficial resem- 

 blance to the ears of corn. Teosinte is cultivated chiefly for soiling. 

 It has sometimes been called Reana luxurians Durieu. 



143. ZEA L., maize, Indian corn. 



Spikelets unisexual; staminate spikelets 2-flowerecl, in pairs, on 

 one side of a continuous rachis, one nearly sessile, the other pedicel- 

 late; glumes membranaceous, acute; lemma and palea hyaline; 

 pistillate spikelets sessile, in pairs, consisting of one fertile floret 

 and one sterile floret, the latter sometimes developed as a second, 

 fertile floret; glumes broad, rounded or emarginate at apex; sterile 

 lemma similar to the fertile, the palea present; style very long and 

 slender, stigmatic along both sides well toward the base. 



A tall annual grass, with broad, conspicuously distichous blades, 

 monoecious inflorescences, the staminate flowers in spikelike racemes, 

 these numerous, forming large spreading panicles (tassels) terminat- 

 ing the stems, the pistillate inflorescence in the axils of the leaves, 

 the spikelets in 8 to 16 or even as many as 30 rows on a thickened, 

 almost woody axis (cob), the whole inclosed in numerous large 

 foliaceous bracts (husks), the long styles (silk) protruding from the 

 top as a silky mass of threads. In the common varieties of corn the 

 floral bracts are much shorter than the kernel and remain on the cob 

 when the kernels are shelled. 1 Species one. 



Type species : Zea mays L. 



Zea L., Sp. PI. 971, 1753; Gen. PI., ed. 5, 419. 1754. Zca mays is the 

 only species described. 



Mays Tourn., in Gaertn. Fruct. and Sem. 1 : 6, pi. 1. 1788. The single species, 

 If. zea Gaertn., is the same as Zea mays L. 



Mayzea Raf., Med. Fl. 2 : 241. 1830. Two species included. Zea mays L., on 

 which the first species, M. ccrealis, is based, is taken as the type. 



In the United States Zea mays L. (figs. 172, 173) is usually called 

 corn; in Europe and sometimes in America, especially in literature, 

 it is called maize. Corn is one of the important economic plants of 

 the world, being cultivated for food for man and domestic animals 

 and for forage. It originated 2 in America, probably on the Mexican 

 Plateau, and was cultivated from prehistoric times by the early 



1 For note on the structure of the maize ear as indicated in Zea-Euchlaena hybrids, see 

 Collins, Journ. Agr. Res. 17: 127-135. 1019. 



2 For a note on the origin of maize, see Collins, Journ. Washington Acad. Sci. 2 : 520. 

 1912. 



