Streamlined Beauties in every Colour. Calla Lilies, sometimes called Arum Lilies, Trumpet Lilies or even Pig Lilies, are indigenous to Southern Africa, but have become increasingly popular in other countries where their unusual flower structure gives a classic style to garden beds, containers, bouquets or arrangements. What appears to be the flower is actually a modified leaf which curls itself into a trumpet-like sheath for the real flowers – a cluster of tiny blooms on a central spadix. The Calla plants with their large bright green leaves, sometimes speckled with white are attractive even before the purple, pink, green, pure white, or yellow Calla “flowers” bloom in late spring or summer. Keep Callas exposed to the sun and in soil that is moist but not soggy.