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.
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.
Geography & Distribution
The arum lily is native to Southern Africa (provinces of Limpopo, North-West, Gauteng, Mpumalanga, Swaziland, Free State, KwaZulu-Natal, Lesotho, Western Cape and Eastern Cape), where it grows in marshy places from 20 to 2250 metres above sea level. It is also widely naturalized throughout the tropics.
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. The fruits are green berries which turn orange at the base when ripe.
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.
Arum lilies in Wolfgat Nature Reserve, Cape Town, South Africa (Image: Wolfgang Stuppy)
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.
In southern Africa where it occurs naturally, the leaves and rhizomes are traditionally used in dressings and oral preparations for a variety of complaints. The rhizomes are edible, although the plant is reportedly toxic.
Scientists have shown that Zantedeschia aethiopica may be useful in artificial wetland systems to clean waste water and prevent algal growth.
Zanthedschia aethiopica (Image: Wolfgang Stuppy)
This moderately hardy monocot can be grown outside in the UK, but at Kew is sheltered under the glass of the Temperate House. 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 and soft. 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: 1
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.
PlantZAfrica.com - provides information about plants native to southern Africa and related topics.
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