Aloe melanacantha A.Berger
Common names: black-thorn aloe, small mountain aloe (Eng.); swartdoringaalywn kleinbergaalwyn, goree (Afr.)
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.
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 stem-less aloes.
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 along the keel and margins of the leaves. The thorns at the leaf bases may be shorter and whitish.
Inflorescences 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.
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 1685 (Court 1981) in Springbok during an expedition of Simon Van Der Stel, first commander at the Cape of Good Hope. 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 epithet melanacantha is from the Greek, melas meaning black and akanthos meaning thorns, alluding to the striking black thorns on the leaves of this plant.
There are approximately Aloe 125 species in South Africa, many of which are important garden plants locally and across the world especially in Mediterranean and temperate regions.
A close relative of Aloe melanacantha is the rare A. erinacea which occurs on the higher mountains further north in Namibia. Aloe erinacea grows in dense clumps and is slightly smaller than its South African relative but is otherwise indistinguishable. A.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.
Aloe melanacantha produces nectar and is pollinated by sun 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 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 them to be dispersed by the wind. The plant in itself is very tough and can often survive 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.
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 it does not thrive away from its 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.
Growing Aloe melanacantha
Aloe melanacantha is best grown from seeds. These 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. ramosissimaand 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.
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Kirstenbosch National Botanical Garden
Plant Type: Succulent
SA Distribution: Northern Cape, Western Cape
Soil type: Sandy, Clay
Flowering season: Autumn, Winter
Flower colour: Red, Yellow
Aspect: Full Sun
Gardening skill: Average