Zantedeschia aethiopica, commonly known as calla lily and arum lily, is a species of flowering plant in the family Araceae, native to southern Africa in Lesotho, South Africa, and Eswatini.

Description

Zantedeschia aethiopica is a rhizomatous herbaceous perennial plant, evergreen where rainfall and temperatures are adequate, deciduous where there is a dry season. Its preferred habitat is in streams and ponds or on the banks. It grows to 0.6 – tall, with large clumps of broad, arrow shaped dark green leaves up to 45 cm long. The inflorescences are large and are produced in spring, summer and autumn, with a pure white spathe up to 25 cm and a yellow spadix up to 90 mm long. The spadix produces a faint, sweet fragrance. Zantedeschia aethiopica contains calcium oxalate, and ingestion of the raw plant may cause a severe burning sensation and swelling of lips, tongue, and throat; stomach pain and diarrhea may occur.

Distribution and habitat

Z. aethiopica is native to southern Africa, specifically Lesotho, Mozambique, South Africa, and Eswatini. It has naturalised in Kenya, Madeira, Azores, Malawi, New Zealand, Tanzania, Zambia, coastal California and Australia, particularly in Western Australia, where it has been classified as a toxic weed and pest. The majority of invasive populations are located in coastal prairies and wetlands near human settlements. It is also a highly invasive species in riparian areas and pastureland of Western Australia and New Zealand. The cultivar 'Green Goddess' is listed in the New Zealand National Pest Plant Accord, which proscribes its cultivation, sale, and distribution. The reproduction of Z. aethiopica involves seeds dispersal by birds and vegetative propagation through rhizomes that can spread when soil or garden cuttings are moved.

Cultivation and uses

A number of cultivars have been selected as ornamental plants: The cultivars 'Crowborough' and 'Green Goddess' have gained the Royal Horticultural Society's Award of Garden Merit. In order to introduce colours to the large white calla lilies, like the many colours available in the dwarf summer calla lilies, attempts have been made to hybridise Z. aethiopica with Z. elliotiana. These have resulted in albino progeny, which are non-viable. Zantedeschia aethiopica can be used for treatment of wastewater due to its tolerance of iron and ability to grow in wet areas.

Symbolism

Until 2011, Zantedeschia aethiopica was the national flower of the island nation of Saint Helena, where it grows widely, but is considered an invasive plant. Further, it is an important symbol of Irish republicanism and nationalism since 1926, because it is used to commemorate the dead of Easter 1916 and onward.

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