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Zantedeschia aethiopica (arum lily)

The striking arum lily has been known to European horticulture since at least the 1660s and is one of the world's most iconic and widely known plants.

White arum lily flower

Zantedeschia aethiopica (Photo: Wolfgang Stuppy)

Species information

Common name: 

arum lily, calla lily

Conservation status: 

Not of conservation concern.

Habitat: 

Marshy places in Southern Africa.

Known hazards: 

All parts of the plant are poisonous, causing irritation and swelling of the mouth and acute gastric diarrhoea.

Taxonomy

Subclass: 
Superorder: 
Lilianae
Order: 
Alismatales
Family: 
Araceae
Genus: Zantedeschia

About this species

Zantedeschia aethiopica is one of the world's most iconic and widely known plants. Although commonly known as the arum lily or calla lily, it is not a lily at all but an aroid, with its brilliant white spathe (floral bract) surrounding the central pale yellow spadix (floral spike) bearing tiny flowers.

This very attractive plant has been known to European horticulture since at least the 1660s. Carl Linnaeus described it in 1753 as Calla aethiopica and it has been commonly known as the calla lily ever since. The species epithet 'aethiopica' refers to the fact that it is native to Africa. In 1826 Sprengel transferred it to a new genus which he called Zantedeschia. According to Cythna Letty (1973), the name was probably given in honour of Giovanni Zantedeschi, an Italian botanist who lived in the early 19th century.

Genus: 
Zantedeschia

Discover more

Geography and distribution

The arum lily is native to South Africa (provinces of Limpopo, North-West, Gauteng, Mpumalanga, Swaziland, Free State, KwaZulu-Natal, Lesotho, Western Cape, Eastern Cape), Lesotho and Swaziland. It grows in marshy places from 20 to 2,250 metres above sea level. Although native to Southern Africa it is also widely naturalised throughout the tropics.

 Zantedeschia aethiopica

Zantedeschia aethiopica

Description

The arum lily is well known for its striking appearance when in flower, with a brilliant white floral bract wrapping around a yellow finger-like projection in the centre. The flowering parts arise from a ring of glossy green leaves. 

Zantedeschia aethiopica is a perennial herb growing up to 60 cm tall (or taller in the shade). It has a thick, fleshy, underground rhizome (swollen stem).

The leaves are evergreen, hairless and form a rosette. The leaves are somewhat leathery, and usually broadly oval with lobes at the base. The inflorescence (flowering part) is on a stalk up to 60 cm long. The spathe (floral bract) is about 15 cm long and 12 cm wide. It is ivory-white on the inside and the outside is bright green at the base and gradually becomes white towards the top. The lower part forms a wide-mouthed funnel, and the much wider upper part spreads out with its tip curled under. The spadix (floral spike) has an upper zone of about 7 cm long, which is covered with tiny bright yellow anthers (male parts). These produce slender threads of white pollen when ripe. The spadix also has a lower zone, which is covered with yellow-green to whitish pistils (female parts) interspersed with mushroom-shaped sterile structures. The fruits are green berries which become soft and orange-coloured at the base when ripe.

Uses

Arum lilies in Wolfgat Nature Reserve, Cape Town, South Africa (Photo: Wolfgang Stuppy)

All parts of the plant are poisonous, causing irritation and swelling of the mouth and acute gastric diarrhoea. The sap can cause eczema and dermatitis of the skin and is also an irritant to the mucous membranes and eyes. In southern Africa, where the species occurs naturally, the leaves and rhizomes are traditionally used to dress wounds and bites. The leaves and rhizomes are also reported to be eaten, but only following careful preparation to remove the needle-like calcium oxalate crystals, known as raphides.  

Due to its striking inflorescences, Zantedeschia aethiopica is very popular as cut flowers and as an ornamental. It is used as a symbol of purity in bridal and funeral flower arrangements.

Scientists have shown that Zantedeschia aethiopica may be useful in artificial wetland systems to clean waste water and prevent algal growth.

Cultivation

Zanthedeschia aethiopica flowers

Zantedeschia aethiopica (Photo: Wolfgang Stuppy)

This moderately hardy monocotyledon can be grown outside in the UK. In any position it will grow best in moist soil or shallow water. In its natural habitat it can be deciduous or evergreen, depending on the rainfall and soil water rather than temperature. The position in which it is planted will also determine size and flowering. Planting under shade is preferable if there is no boggy position for this plant, but this will reduce the number of flowers and result in a smaller plant. Fertile soil is required. In optimum conditions a good display of flowers can be enjoyed in the spring and summer.

Propagation can be by seed or division. Seeds can be removed from the pulp of the fruit when it has turned yellow or orange and soft but gloves should be worn due to the toxicity of the plant. The seeds should then be dried off for sowing in the spring. They should be sown sparingly to allow space for the fleshy roots to form. A seed compost should be used and the seeds covered lightly. Division of the fleshy rootstock should be done when the plant is dormant. It can then be planted at a depth of 5 cm.

Millennium Seed Bank: Seed storage

Kew's Millennium Seed Bank Partnership aims to save plant life worldwide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.

Number of seed collections stored in the Millennium Seed Bank: One
Germination testing: Successful

Arum lily at Kew

You can see Zantedeschia aethiopica growing at Kew in the Duke's Garden, on the south side by the wall. There are also extensive plantings along the stream in the Secluded Garden, and a large planting of the popular cultivar ‘Crowborough’ can be seen in the Plant Family Beds.

References and credits

Belmont, M.A. & Metcalfe, C.D. (2003). Feasibility of using ornamental plants (Zantedeschia aethiopica) in subsurface flow treatment wetlands to remove nitrogen, chemical oxygen demand and nonylphenol ethoxylate surfactants - a laboratory-scale study. Ecological Engineering 21: 233-247.

Germishuizen, G. & Meyer, N.L. (eds) (2003). Plants of southern Africa: an annotated checklist. National Botanical Institute, Pretoria (Strelitzia vol. 14), p. 972.

Hutchings, A., Haxton Scott, A., Lewis, G. & Cunningham, A. (1996). Zulu Medicinal Plants: an Inventory. University of Natal Press, Pietermaritzburg.

Letty, C. (1973). The genus Zantedeschia. Bothalia. 11: 5-26.

Singh, Y., van Wyk, A.E. & Baijnath, H. (1995). Know your arums: an easy guide to identify members of the genus Zantedeschia. Veld & Flora 81: 54-55.

South African National Biodiversity Institute's plant information website: www.plantzafrica.com

van Wyk, B.-E., van Oudtshoorn, B. & Gericke, N. (2009).  Medicinal Plants of South Africa.  Briza Publications, Pretoria.

Kew Science Editor: Simon Mayo [further edit by Steve Davis and Rhian Smith - 30 June 2014]
Kew contributors: Emma Crawforth
Copyediting: Emma Tredwell

While every effort has been taken to ensure that the information contained in these pages is reliable and complete, the notes on hazards, edibility and suchlike included here are recorded information and do not constitute recommendations. No responsibility will be taken for readers’ own actions.

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