Sp. Pl. 2: 968. 1753; Gen. Pl. ed. 5; 414, 1754.
Herbs, wetland. Rhizomes horizontal. Leaves appearing before flowers, several, emergent, arising along rhizome, also clustered terminally; petiole 1.5–2 or more times as long as blade; blade bright green, simple, not peltate, ovate to nearly round, base cordate, apex short-acuminate to apiculate; lateral veins parallel. Inflorescences: peduncle erect, as long as or longer than petiole, apex not swollen; spathe white, often green or partially green abaxially, not enclosing spadix; spadix cylindric. Flowers all bisexual or distal ones staminate; perianth absent. Fruits not embedded in spadix, red. Seeds 4–9(–11), embedded in mucilage. x = 18.
Numerous cytogenetic studies have been conducted on Calla with both diploid (2n = 36) and apparently tetraploid (2n = 72) populations reported (see G. Petersen 1989). All counts from North American populations counted have a somatic number of 36 chromosomes.