Plants annual. Culms (0.5)1-3(6) m tall, (0.5)1-5 cm thick. Bladesmostly 30-90 cm long, 2.5-12 cm wide. Pistillate inflorescencesrames or spikes, usually shortly pedunculate (sometimes sessile), solitary, 4-30(40) cm long, (0.5)1-10 cm thick, with 2 or more rows of paired spikelets, hence the spikelets 4 or more ranked, rarely terminating in an unbranched staminate inflorescence. Caryopsesconcealed in fruitcases (wild taxa) or exposed (domesticated taxon); fruitcases of wild taxa distichous, triangular in side view; domesticated taxon without fruitcases, glumes reduced and shallow or collapsed and embedded in the rachis. Staminate panicles 10-25+ cm, with 1-60(235) branches, internodes 1.5-8.2 mm; spikelets 9-14 mm long, 2.5-5 mm wide; lower glumesrounded dorsally, flexible, translucent, papery, loosely enclosing the upper glumes, the 2 lateral veins subequal to the others, not winged. 2n = 20.
Of the five subspecies of Zea mays, only the domesticated subspecies, Z. mays subsp. mays, is widely grown outside of research programs. Three wild subspecies are treated here, albeit briefly, because of their importance as genetic resources for Z. mayssubsp. mays.