Aloe africana Mill. (Uitenhage aloe) is a single-stemmed tree-aloe endemic to the Eastern Cape province of South Africa, where it grows on rocky hillsides and in valley bushveld between sea level and about 600 m. It reaches three to four metres in habitat, occasionally taller, making it one of the medium-sized South African tree-aloes in the same broad size class as A. ferox and smaller than A. pluridens.
Part of the Complete Aloe Guide.
Identification
A solitary trunk crowned by a dense rosette of 30 to 50 glaucous-green leaves, each 60 to 80 cm long and 7 to 10 cm wide at the base, tapering to an acute tip. Leaf margins carry prominent reddish-brown teeth. The trunk retains its dried dead leaves in a persistent skirt (marcescence), a shared feature with A. ferox though more pronounced in habitat than under cultivation.
The diagnostic feature is the inflorescence. A. africana produces a multi-branched panicle with cylindrical racemes that curve downward at the tip in a distinctive S-shape, carrying orange-yellow tubular flowers in late winter. The downward-curving raceme is unusual in the genus and separates this species from the superficially similar A. ferox, whose raceme stays upright. Flowering in cultivation outside its native range is possible only in large specimens grown in ground in frost-free Mediterranean climates.
Cultivation
Standard cultivation for robust South African aloes applies. Full sun at any latitude, mineral-heavy free-draining substrate, deep but infrequent watering through the active season. A. africana is somewhat more frost-tolerant than most tree-aloes at the juvenile stage; mature specimens in dry winter conditions tolerate brief drops to −4°C without lasting damage.
The species grows slowly compared with A. arborescens and takes fifteen to twenty years to reach flowering size from seed. A juvenile rosette in a 20 cm pot will be happy for five to ten years before it begins to lift on a visible trunk. Pot size should be adequate but not generous; aloes in oversized pots retain wet substrate around unused roots and rot at the base.
Propagation
Seed is the only route of practical consequence. A. africana is solitary and does not produce basal offsets except rarely as a response to apical damage. Two unrelated plants flowering simultaneously are required for viable seed; this is the bottleneck for amateur propagation because cultivated material tends to trace to a handful of clones and suffers self-incompatibility. Fresh seed sown on sterile mineral mix germinates in two to three weeks at 22 to 26°C, and seedlings reach the one-year size of a 5 cm plant with two or three juvenile leaves.
Stem cuttings are not viable; the trunk is too woody and the species does not root along its length in the way A. arborescens does.
Notes
A. africana is sometimes sold in the general trade as a substitute for A. ferox because both are tall single-trunked South African aloes. The adult inflorescence distinguishes them, and juvenile plants can be separated on leaf colour (bluer in A. africana) and tooth distribution (A. ferox has larger, more widely spaced teeth, often with additional teeth on the upper leaf surface).
The species hybridises readily with A. ferox, A. arborescens, and A. speciosa where ranges overlap in the Eastern Cape, and intermediate specimens in cultivation are common. If you want true A. africana, buy from a specialist nursery with documented seed provenance.