n. [capitalized] A genus of araceous plants, of a single species, C. palustris, the water-arum, which occurs in cold marshes in Europe and North America.n. A plant of the genus Calla.n. A plant of the allied genus Richardia, or, according to the latest authorities, Zantedeschia: the common calla of house-cultivation. It is often erroneously called calla-lily, from the lily-like appearance of its pure-white flowers.