Zea mays

Plants annual. Culms (0.5)1-3(6) m tall, (0.5)1-5 cm thick. Blades mostly 30-90 cm long, 2.5-12 cm wide. Pistillate inflorescences rames 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. Caryopses concealed 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 glumes rounded 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. mays subsp. mays.

Annual herb 0.5 - 6.25 m tall Leaves: borne along the culm, with open sheaths and membranous ligules having short hairs along the margins. The flat blades are 30 cm - 0.9 m long and 2.5 - 12 cm wide. Inflorescence: either male or female. The male inflorescence (tassel) is borne terminally, 10 - 25 cm or longer, with up to 235 branches. Female inflorescence a terminal spike (ear) on an axillary branch, 4 - 40 cm long, 0.5 - 10 cm across, with two or more rows of paired spikelets. Cultivated female inflorescences are surrounded by many modified leaves (husks). Fruit: a caryopsis, surrounded by a fruitcase (the spikelet and part of the branch) in wild subspecies, exposed in cultivated plants. Culm: erect, 0.5 - 6 m long, 0.5 - 5 cm across, the internodes spongy in the center (pith). Spikelets: either stalkless or stalked. The male spikelets are paired, 9 - 14 mm long, 2.5 - 5 mm wide, with each spikelet having two male florets. The 60 to more than 1000 female spikelets of cultivated plants are found in eight to 24 rows, with each spikelet having one functional floret. Glumes: of male spikelets translucent and papery, with the lower glumes rounded on the back, flexible, and losely covering the upper glumes. Glumes of female spikelets are rudimentary. Florets: having transparent, unawned lemmas and paleas. Female florets have long, thin styles (silks), and male florets have three anthers.

Similar species: No information at this time.

Flowering: June to September

Habitat and ecology: Introduced from tropical America, this is a common crop species that often grows near grain elevators, on railroad ballast, and along road shoulders.

Occurence in the Chicago region: non-native

Etymology: Zea comes from the Greek name of a different grain. Mays means "our mother."

Author: The Morton Arboretum