Calla Lilies (Zantedeschia species) aren't really lilies and their "flower" isn't a flower, but a spathe--a modified leaf that protects the tiny true flower(s) inside. This beautiful sunshine-yellow calla, Zantedeschia elliottiana, or Yellow Mini Calla, is either the 'Millenium' or 'Sunshine Gold' variety, says Lee. Mini Callas grow 10-12 inches tall with a 2-3-inch spathe. Regular callas reach 2-3 feet with 6-8-inch spathes. Callas like sun and moist soil. They grow from rhizomes that in the Ozarks should be lifted and stored before winter. Caution: Calla lilies are highly toxic to both humans and animals.