Herbs, perennial, from rhizomes. Aerial stems present, unbranched. Leaves cauline, 2-ranked, differentiated into basal sheath, petiole, and blade; sheaths overlapping, supporting stem, open, ligule absent; summit of petiole not differentiated; blade with lateral veins parallel, diverging from prominent midrib. Inflorescences 1 per aerial shoot, terminal on leafy shoot, pedunculate racemes or panicles of flowers or of 2-flowered monochasial cymes (cincinni); bracts of main axis subtending flowers or cincinni. Flowers bisexual, asymmetric; sepals and petals differentiated, sepals 3, distinct, petals 3, connate at base; fertile stamens 1, petal-like, anther marginal, 1-locular; staminodes (1--)3--4, petal-like, showy, unequal, anterior staminode (labellum) often broader than posterior staminodes; ovary inferior, 3-carpellate, 3-locular, all locules fertile; placentation axile; ovules few to numerous per locule; style standing away from stamens and staminode, petal-like; stigmatic area shaped as marginal callosity; style, stamen, and staminodes basally connate into tube. Fruits capsules; sepals persistent in fruit. Seeds: aril absent; endosperm scanty; perisperm copious; embryo straight. x = 9.

The flowers of Cannaceae are showy and brightly colored with foliaceous or petal-like sepals and have a conspicuously warty or spiny-fimbriate ovary. The fruits are large, broadly ellipsoid, loculicidal, and warty or spiny-fimbriate. The seeds are very hard with an ovoid to globose shape.

Cannaceae are most closely related to the Marantaceae, the prayer-plants, with which they share several unusual reproductive features, such as asymmetric flowers, a reduction in the number of pollen-bearing stamens to a single bisporangiate anther, and secondary pollen presentation (P. F. Yeo 1993). The pollen grains are large and spheroid, and, like those of most members of the order Zingiberales, have a much reduced exine and a much expanded intine layer.