Calla (Bog Arum, Marsh Calla, Wild Calla, and Water-arum) is a genus of flowering plant in the family Araceae, containing the single species Calla palustris. It is native to cool temperate regions of the Northern Hemisphere, in central, eastern and northern Europe (France and Norway eastward), northern Asia and northern North America (Alaska, Canada, and northeastern contiguous United States).
The plant is very poisonous when fresh due to its high oxalic acid content, but the rhizome (like that of Caladium, Colocasia, and Arum) is edible after drying, grinding, leaching and boiling.
The genus formerly also included a number of other species, which have now been transferred to the separate genus Zantedeschia. These plants, from tropical Africa are, however, still often termed “calla lilies”, but should not be confused with C. palustris.
Photos: Celeste Mookherjee