Zea mays
Zea mays subsp. mays
corn, cultivated corn
corn, Indian corn, mais, maize
(0.5)1-3(6) m tall, (0.5)1-5 cm thick.
(1)2-4(6) m tall, (1)2-5 cm thick.
mostly 30-90 cm long, 2.5-12 cm wide.
50-90 cm long, 3-12 cm wide.
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.
60-1000+, exposed and naked.
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.
inflorescences spikes, 15-25(40) cm long, 2-5(10) cm thick, cylindrical, tightly and permanently enclosed in several to many leaf sheaths and a large prophyll, with 8-24 or more rows of paired spikelets on a thickened, strongly vascularized, tough rachis (cob), not disarticulating at maturity;
fruitcases not developed, rachis internodes fused into the extra-vascular cylinder, glumes reduced, shallow.
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.
panicles with a polystichous central axis and non-disarticulating branches;
central axes usually much denser and thicker than the usually distichous lateral branches, these lacking abscission layers.
= 20.
= 20.
Zea mays
Zea mays subsp. mays
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Zea mays subsp. mays is the familiar domesticated corn (or maize), from which around 400 indigenous races and many different kinds of cultivars have been developed. It is an obligate cultigen, unable to persist outside of cultivation because the caryopses are permanently attached to the rachis and enclosed by the subtending leaf sheaths. Supersweet cultivars have a double recessive gene that delays the conversion of sugar to starch; flint corns have unusually hard endosperm; and waxy cultivars have endosperm with an unusually high level of proteins and oils. Popcorns have a core of soft, relatively moist endosperm surrounded by hard endosperm. The grains "pop" when heat causes the moisture of the inner endosperm to vaporize.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Pistillate inflorescences cylindrical spikes, 2-5(10) cm thick, with 8-24+ rows of spikelets pairs, each inflorescence tightly and permanently enclosed by several leaf sheaths and a large prophyll, not disarticulating at maturity; caryopses 60-1000+, not concealed by the glumes; staminate panicle branches not disarticulating below the sessile spikelets, lacking abscission layers; central axis of the staminate panicles polystichous, much thicker than the lateral branches; obligate domesticate | subsp. mays |
1. Pistillate inflorescences cylindrical, distichous rames, less than 1 cm thick, with 2 rows of spikelet pairs, each rame usually enclosed by a single leaf sheath and a prophyll, disarticulating at maturity into fruitcases; caryopses 4-15, each one concealed within a fruitcase; staminate panicles composed of rames that disarticulate below the sessile spikelets and have evident abscission layers; central axis of the staminate panicles similar in width to the rames; in the Flora region, wild taxa are known only from research plantings. | → 2 |
2. Staminate spikelets (6.6)7.5-10.5 mm long; fruitcases 6-10 mm long, 4-6 mm wide; staminate panicles with 1-35+ ascending to divergent, rather stiff branches | subsp. mexicana |
2. Staminate spikelets 4.6-7.2(7.9) mm long; fruitcases 5-8 mm long, 3-5 mm wide; staminate panicles usually with 10-100(235) divergent to nodding branches. | → 3 |
3. Leaves pubescent; staminate panicles with (2)10-100(235) branches | subsp. parviglumis |
3. Leaves glabrous or almost so; staminate panicles usually with fewer than 40 branches | subsp. huehuetenangensis |
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