. . . among the eight recognized species of calla lily the Zantedeschia aethiopica is strong and sturdy, growing in many soils and habitats, multiplying by rhizome offsets . . . it is naturalised and regarded as a weed throughout much of the world . . . the calla lily is poisonous, producing irritation and swelling of the mouth and throat, acute vomiting and diarrhea . . .