Zantedeschia (pronounced ) is a genus of herbaceous flowering plants in the family Araceae, native to southern Africa from South Africa north to Malawi. The name of the genus was given as a tribute to Italian botanist Giovanni Zantedeschi (1773–1846) by the German botanist Kurt Sprengel (1766–1833). Common names include arum lily for Z. aethiopica, calla, and calla lily for Z. elliottiana and Z. rehmannii although it is neither a true lily (Liliaceae), nor Arum or Calla (related genera in Araceae). It is also often erroneously spelled as "cala lily". It has often been used in many paintings, and is visible in many of Diego Rivera's works of art (see The Flower Vendor, amongst others).
The Zantedeschia are rhizomatous herbaceous perennial plants growing to 1-2.5 m tall with leaves 15–45 cm long. The inflorescence is a showy white, yellow or pink spathe shaped like a funnel with a yellow, central, finger-like spadix.
The Zantedeschia species are poisonous due to the presence of calcium oxalate. "All parts of the plant are toxic, and produce irritation and swelling of the mouth and throat, acute vomiting and diarrhea." However leaves are sometimes cooked and eaten.
All species are endemic to southern Africa. Z. aethiopica grows naturally in marshy areas and is only deciduous when water becomes scarce. It grows continuously when watered and fed regularly and can survive periods of minor frosts. Z. aethiopica is a very strong and sturdy plant, being able to grow in many soils and habitats, multiplying by rhizome-offsets; it is naturalised and regarded as a weed throughout much of the world. Z. odorata is a rare species, resembling Z. aethiopica, but deciduous and smelling like freesia, endemic to a few localities in South Africa. Z. albomaculata is a widespread and variable species, growing from South Africa north to Kenya, varying in shades of white to cream and pink to orange-shades. Z. elliotiana is known from horticultural sources only and is probably of hybrid origin. Z. jucunda and Z. pentlandii are rare species with beautiful large yellow showy flowers. Z. rehmannii is a pink-flowered species with sword shaped leaves.
All Zantedeschias produce large, showy flowers spathes and are often grown both as ornamental plants and for cut flowers. Zantedeschia are hardy plants, but some are more winter-hardy than others. The white Zantedeschia aethiopica and some of its relatives can survive at minimum winter temperatures below -23 °C (USDA Zone 6) and many others can be grown in even warmer areas where all the ground does not freeze (USDA Zone 7). Some species are less hardy and can only survive winter temperatures to -12 °C (Zones 8). This plant must be grown as tender bulbs or houseplants in cooler areas. Species and hybrids between Z. elliotiana, Z. jucunda, Z. pentlandii and Z. rehmannii appear to have an optimum temperature for growth near 25 °C, with growth being suppressed once daily average temperatures persist at 28 °C.
Extensive commercial production of Zantedeschia for cut flowers and/or planting material occurs in California, Colombia, New Zealand and Kenya[7]. Plant breeders in California and New Zealand continue to produce an extensive range of new hybrid cultivars.
In the South-West of Western Australia, Z. aethiopica was introduced for horticulture. It has become a widespread and conspicuous weed of watercourses, heath, and wetter pastures.
The so-called white calla is derived from Z. aethiopica. All varieties with flowers with shades of yellow, orange, red, purple are mainly derived from Z. albomaculata, Z. pentlandii and Z. rehmanni.