768 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



3. Tripsacum lanceolatum Rupr. Mexican gamagrass. (Fig. 

 1694.) Resembling T. dactyloides ; sheaths, especially the lower, 

 sometimes hispid; blades often hispidulous on the upper surface; 

 spikes more slender with smaller spikelets than in T. dactyloides, 

 the terminal spikes usually 3 to 5 ; staminate spikelets membranaceous, 

 one of the pair distinctly pediceled. % (T. lemmoni Vasey.) — 

 Rocky hills, Huachuca Mountains, Ariz. ; Mexico to Guatemala. 



158. EUCHLAENA Schrad. Teosinte 



Staminate spikelets as in Zea; pistillate spikelets solitary on 

 opposite sides, sunken in cavities in the hardened joints of an 

 obliquely articulate rachis, the indurate first glume covering the 

 cavity; second glume membranaceous, the lemma hyaline. Spikes 

 infolded in foliaceous spathes or husks, 2 to several of these together 

 enclosed in the leaf sheaths. Robust annuals and perennials with 

 broad flat blades, terminal panicles of staminate spikelets, and axillary 

 spikes of pistillate spikelets. Type species, Euchlaena mexicana. 

 Name from Greek eu, well, and chlaina, cloak, alluding to the husks 

 hiding the pistillate inflorescence. 



1. Euchlaena mexicana Schrad. Teosinte. (Fig. 1695.) Tall 

 annual, resembling maize, the culms branching at base, 2 to 3 or even 

 5 m tall; blades as much as 8 cm wide, o — Occasionally culti- 

 vated in the Southern States for green forage; Mexico. Thought 

 to be one of the species from which maize originated (see note under 

 Zea mays). 



Euchlaena perennis Hitchc, Mexican teosinte, a perennial species 

 from Mexico, is cultivated at the substation of the Agricultural 

 College, Angleton, Tex., and mob ably at other points. It propagates 

 by creeping rhizomes. 



159. ZEA L. 



Spikelets unisexual; staminate spikelets 2-flowered, 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 

 and fertile lemmas hyaline, the palea developed; style very long and 

 slender, stigmatic along both sides well toward the base. Robust 

 annual, with terminal panicles (tassels) of staminate racemes, and 

 short-peduncled, pistillate, 8- to many-rowed spikes (ears) enclosed in 

 numerous spathes (husks). Type species, Zea mays. Name Greek 

 zea, or zeia, a kind of grain. 



1. Zea mays L. Maize, Indian corn. (Fig. 1696.) Tall 

 robust monoecious annual, with overlapping sheaths and broad, 

 conspicuously distichous blades; staminate spikelets in long spike- 

 like racemes, these numerous, forming large spreading terminal 

 panicles; pistillate inflorescence in the axils of the leaves, the spike- 

 lets in 8 to 16 or even as many as 30 rows on a thickened, almost 

 woody axis (cob), the whole enclosed in numerous large foliaceous 

 bracts or spathes, the long styles (silk) protruding from the summit 

 as a mass of silky threads; grains at maturity greatly exceeding 

 the glumes. Q 



