Aloe melanacantha

A.Berger

Family : Asphodelaceae
Common names : klein bergalwyn, goree (Afr.)

Aloe melanacantha

The true beauty of Aloe melanacantha can only be appreciated when seen flowering in the veld. Its formidable black thorns add an exquisite dimension when viewed in contrast to its bright rocket-shaped flowers that protrude from the rounded plant bodies.

Description
The rounded, ball-shaped rosettes, firm brownish green leaves and the particularly long black thorns on the margins and keel are unmistakable identification clues of Aloe melanacantha or goree as it is known by the locals in Namaqualand. Plants grow as single rosettes or more often in groups of up to 10 or more dense plants. The stems are short and inconspicuous even in old specimens, hence classified as stemless aloes.

Thorns on leaves

The leaves are narrowly triangular, up to 250 mm long and 40 mm wide at the base, then curving gracefully upwards and inwards resulting in the neat and rounded appearance. The leaf is a peculiar brown-green that turns a pinkish red when exposed to prolonged periods of drought and intense heat. The leaves are firm and have a surface that feels rough to the touch. The abundant large black thorns are arranged singularly along the keel and margins of the leaves. The thorns at the leaf bases may be shorter and whitish.

Flower of A. melanacanthaInflorescences are usually simple up to 1 m (40") high, with a single oblong rosette of about 200 (8") x 80 mm (3"). The flowers are tubular, bright red but turn yellow after opening, and bloom in the winter (May-June). As with other aloes, the seeds are typically winged, small, up to 3 mm and produced in abundance inside the fruit capsules that split into three when ripe. Seeds ripen normally around August-September.

Conservation status
Aloe melanacantha is not threatened, primarily due to its relatively established and wide distribution.

Distribution and habitat
Aloe melanacantha grows in rocky or sandy soils; mostly granite derived and prefers the arid conditions of Namaqualand and the Richtersveld. The plants are found from Nieuwoudtville and Bitterfontein northwards to southern Namibia, and grow at altitudes ranging from 50 to 700 m (160 to 2300'). The associated vegetation is predominantly the Namaqualand and Succulent Karoo veld of South Africa.

Derivation of name and historical aspects
Aloe melanacantha was discovered in Springbok during Simon Van Der Stel's (the first commander at the Cape of Good Hope in 1679) expedition in 1685 (Court 1981). The name Aloe is derived from the Arabic, alloch and translated as allal in Greek and Hebrew literally meaning bitter or bitter sap which is descriptive of aloe sap. The species name melanacantha is from the Greek language and is composed of two parts namely melas meaning black, and akanthos meaning thorns, alluding to the striking black thorns found on the leaves of this plant. A close relative of Aloe melanacntha, the very rare A. erinacea, occurs on the higher northern mountains. Aloe erinacea grows in dense clumps and is slightly smaller than its South African relative but is otherwise indistinguishable. Aloe melanacantha is placed in an artificial group of stemless aloes which are mostly unrelated but share a stemless or short-stemmed growth habit. Other species in this group include Aloe peglerae, A. broomii, A. polyphylla, A. cryptopoda, A. gloubuligemma, A. haemanthifolia and a number of other species. There are approximately 125 species of Aloe in South Africa, many of which are important garden plants locally and across the world especially in Mediterranean and temperate regions.

Ecology
Aloe melanacantha produces nectar and is therefore pollinated by sugar birds as well as winged and crawling insects such as ants which are small enough to enter the flower tube in which the nectar is stored. After fertilization, the fruit, which is called a capsule, grows quickly and splits into three parts in spring and summer. The seeds are small, up to 4 mm and slightly winged, enabling it to be dispersed by the wind. The plant in itself is very tough and can survive often for several seasons without water, at which point the leaves turn reddish, a sign generally associated with stress. Aloe melanacantha is not known to be eaten by animals, due to its thorny armour. This is one of many adaptations that low-growing plants such as A. melanacantha use to deter herbivorous animals.

Uses and cultural aspects
No medicinal or cultural uses are recorded for Aloe melanacantha. Obviously they make very attractive garden specimens if successfully cultivated; however, collecting this aloe is wasteful and causes unnecessary damage, because they do not thrive away from their natural habitat. Plants might survive in hot glasshouses but if the light is too soft and temperatures too low, they may lose their characteristic form very quickly.

Flowering in consevatory at Kirstenbosch

Growing Aloe melanacantha

Aloe melanacantha is best grown from seeds. Seeds must be sown as fresh as possible. When kept too long they are parasitized by small crawling insects. The best time for sowing would be in the summer from October to December. Use coarse river sand and cover seeds lightly, then keep moist. It is advisable to treat seeds with a long-lasting fungicide, as seedlings are prone to damping off, a fungus that eventually kills the young plants. Simply shake seeds in a container with some fungicide. After germination, when plants are about 20-30 mm, plant over using a sandy loam medium and feed with organic-based fertilizer at least once a month to ensure healthy growth. If the garden has clay soil, use some agricultural lime and bone meal to break up and nourish the soil. Mature plants in cultivation may at times be subjected to attack from scale insects and aphids. For scale insects an oil-based solution can be used, even soapy water has proven effective against scale. Contact insecticides for insects usually work well but in heavy infestations, a systemic application may be necessary. All known garden pests can be kept to a minimum by simply ensuring optimal growing conditions and healthy plants. Companion plants to Aloe melanacantha include A. pearsonii, A. claviflora, A. falcata, A. gariepensis, A. dichotoma, A. dichotoma subsp. ramosissima and A. arenicola.. Other plants to consider are Lampranthus multiradiatus, L. aureus, Pelargonium echinatum, P. xerophytum, P. spinosum, P. sericifolia, P. crithmifolium, Tripteris oppositifolium, Stoeberia arborescens, Gazania krebsiana, Hermannia saccifera, Lampranthus reptans and Oscularia deltoides. Larger succulents such as Tylecodon paniculatus, Cyphostemma juttea and Cotyedon orbiculata are also suitable choices.

References

  • Court, D. 1981. Succulent flora of southern Africa. Balkema, Cape Town.
  • Cowling, R. & Pierce, S. 1999. Namaqualand, a succulent desert. Fernwood Press, Cape Town.
  • Germishuizen, G. & Meyer, N.L. (eds). 2003. Plants of southern Africa : an annotated checklist. Strelitzia 14. National Botanical Institute, Pretoria.
  • Jackson, W.P.U. 1990. Origins and meanings of South African plant genera. Univeristy of Cape Town Ecolab, Cape Town.
  • Leistner, O.A. 2005. Seed plants of southern and tropical Africa : families and genera. Southern African Botanical Diversity Network Report No. 26. SABONET, Pretoria.
  • Nichols, G. 2005. Growing rare plants. Southern African Botanical Diversity Network Report No. 36. SABONET, Pretoria.
  • Smith, C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35. Botanical Research Institute, Pretoria.
  • Stearn, W.T. 2003. Stearn's dictionary of plant names for the gardener. Cassel, UK.
  • Van Wyk, B-E. & Gericke, N. 2000. People's plants. A guide to useful plants of southern Africa. Briza Publications, Pretoria.
  • Van Wyk, B-E. & Smith, G. 1996. Guide to aloes of South Africa. Briza Publications, Pretoria.
  • Van Jaarsveld, E., Van Wyk, B-E. & Smith, G. 2000. Succulents of South Africa. Tafelberg, Cape Town.
  • Van Wyk, A.E. & Smith, GF. 2001. Regions of floristic endemism. Umdaus Press, Hatfield, Pretoria.
  • Williamson, G. 2000. Richtersveld, the enchanted wilderness. Umdaus Press, Hatfield, Pretoria.

 

If you enjoyed this webpage, please record your vote.

Excellent - I learnt a lot
Good - I learnt something new

Werner Voigt
Kirstenbosch NBG
June 2007


 

 

 

 

 

To find out if SANBI has seed of this or other SA species, please email our seedroom.


This page forms part of the South African National Biodiversity Institute's plant information website www.plantzafrica.com

 


 

SANBI Home