Corn is a tall annual herb. Culm erect, usually unbranched, 1-4 m tall. Leaf sheath with transverse veins; Lingual membranous, ca. 2 mm long; The blades are flat and broad. Terminal male panicle large, male spikelets twin, up to 1 cm long. Caryopsis globose or oblate, usually 5-10 mm long. Flowers and fruits in autumn.