Aloe arborescens Mill.
Common names: krantz aloe (English), kransaalwyn (Afrikaans), ikalene (Xhosa), inkalane or umhlabana (Zulu)
SA Tree No: 28.1
The krantz aloe is a valuable garden asset, it has large beautiful flowers, attractive foliage, decorative form, and it is easy to grow. It is also a 'must-have' for anyone wanting to stock their herb gardens with indigenous healing plants.
The krantz aloe develops into a multiheaded shrub 2 -3m high with striking grey green leaves arranged in attractive rosettes. The leaf margins are armed with conspicuous pale teeth.
The large colourful flower spikes are borne in profusion during the cold winter months (May-July), brightening up a drab winter garden. Deep orange is the most common colour, but there are also pure yellow forms, and an unusual bi-coloured form of deep orange (almost red) and yellow. The inflorescence is usually unbranched, with two to several arising from a single rosette. As with all the aloes, the flowers produce nectar and are attractive to many kinds of birds, in particular the small and colourful sunbirds, which flit from flower to flower in search of nectar. The flowers also attract bees.
The species formerly known as Aloe mutabilis is now regarded as a synonym of Aloe arborescens. It is a cliff dwelling form with smaller, less branched rosettes and red & yellow bi-coloured flower spikes and is more evident on the high inland plateau of the northern provinces of South Africa. This cliff dwelling form of Aloe arborescens can be seen hanging from the cliffs alongside the waterfall at the Witwatersrand National Botanical Garden.
Although it is in fact a large much-branched shrub, Aloe arborescens has been allocated a national tree number (28.1).
Distribution and habitat
This species is distributed mainly over the eastern, summer rainfall areas of the country. It has the third widest distribution of any aloe, occurring from the Cape Peninsula along the eastern coast, through KwaZulu-Natal, Mpumalanga and Limpopo province and further north into Mozambique, Zimbabwe and Malawi. It is one of the few aloes that can be found growing at sea level right up to the tops of mountains. The krantz aloe is adapted to many habitats, but is usually found in mountainous areas where it favours exposed ridges and rocky outcrops. It is also found in dense bush.
Derivation of name and historical aspects
The name aloe is from the Greek alsos and refers to the bitter juice from the leaves of these plants. It is probably derived from the earlier Arabic word alloeh or the Hebrew word allal, both meaning bitter. The Latin word arborescens means tree-forming or tree-like, and is a bit misleading in that this aloe is not really tree-like, but the name was originally applied to this species in reference to the stem-forming habit. The common name krantz aloe refers to its habitat, a krantz being a rocky ridge or cliff.
Aloe arborescens is one of approximately 130 Aloe species native to southern Africa. It is possibly the most widely cultivated aloe in the world and can be seen grown in gardens in many cities around the world. It was one of the first South African aloes collected and planted in the Company's Garden in Cape Town. It was grown in Amsterdam by Professor Commelin in 1674, and featured in Hort. Amst. 2 in 1701.
In many parts of South Africa Aloe arborescens is planted around kraals (domestic stock enclosures) as a living fence. It often happens that the position of old kraals can still be seen many years after they have been abandoned because the aloes persist. Cuttings intended for use as barrier plants are sold in muthi shops.
The Zulu people use the leaves of this plant, dried and pounded into a powder, as a protection against storms. Decoctions of the leaves are also used in childbirth and in treating sick calves. In the Transkei it is used for stomach ache and given to chickens to prevent them from getting sick. In the Orient, this aloe is grown in domestic gardens as a convenient first-aid treatment for burn wounds and abrasions. In fact it was only after it was used to treat irradiation burn victims of Hiroshima that its healing properties received attention from the West. Extracts from the leaves have been widely investigated since then and shown significant wound healing, anti-bacterial, anti-ulcer, anti-inflammatory, anti-carcinogenic, hypoglycaemic and also alopoeic activity. The leaves have also been found to have purgative properties and the leaf sap is reported to relieve x-ray burns.
Growing Aloe arborescens
The krantz aloe is an easy and rewarding plant to grow, and is a popular garden plant in many countries. It enjoys full sun, well-drained, compost-enriched soil and can tolerate moderate frost but is sensitive to severe frost. It is fast-growing, and it will tolerate drought and neglect once established. It is grown mainly as an ornamental or as an accent plant, but is also an excellent and impenetrable hedge plant.
The krantz aloe is easily propagated from a branch or stem cut off, allowed to dry for a day or so until the wound has sealed, and then planted in well-drained soil or sand. They need not be rooted in any particular place and then transplanted, but can be placed directly into their permanent place in the garden. It is important to remember not to water the cuttings too heavily; overwatering may cause them to rot. This aloe can also be grown from seed, sown in spring. Seed should take three to four weeks to germinate, and the seedlings must be protected from frost.
Aloe arborescens hybridises readily with other aloes.
- Van Wyk, B.E. & Smith, G. 1996. Guide to the Aloes of South Africa. Briza Publications, Pretoria.
- Jackson, W.P.U. 1990. Origins and Meanings of Names of South African Plant Genera. U.C.T. Printing Dept., Cape Town.
- Hutchings, Anne. 1996. Zulu Medicinal Plants, an inventory. University of Natal Press, Pietermaritzburg
- Palmer, E. and Pitman, N. 1972. Trees of Southern Africa. A.A. Balkema, Cape Town.
- van Wyk, B.E., Gericke, N. 2000. People's Plants. Briza Publications, Pretoria.
- Leistner, O.A. (ed.). 2000 Seed plants of southern Africa: families and genera, Strelitzia 10. National Botanical Institute, Pretoria
Andrew Hankey (2001) & Alice Notten (2004)
Witwatersrand NBG & Kirstenbosch NBG
May 2001 updated
Plant Type: Shrub, Succulent, Tree
SA Distribution: Eastern Cape, Gauteng, KwaZulu-Natal, Limpopo, Mpumalanga, North West, Western Cape
Soil type: Sandy, Loam
Flowering season: Autumn, Winter
PH: Acid, Neutral
Flower colour: Red, Yellow, Orange
Aspect: Full Sun
Gardening skill: Easy