Description: Aloe rupestris is a robust fast growing mostly single stemmed tree aloe with very showy flowers. It can grow usually up to 3 m tall (max. 8 m tall) Offsetting forms have been favoured in cultivation.
Stem: Thick, shaggy below, with withered and blackened remains of leaves clothing the upper part, naked on the lower part. The stem often needs support. In habitat it grows in bushes or next to a tree which gives support. The pith is soft, light and spongy.
Roots: It has a spread-root-system the roots are somewhat fleshy.
Leaves: In a compact spiralled rosette at the stem apex in old plants, but in juvenile plants they are ranked in vertical rows. They are strap-like, spreading and recurved, lamina up to about 70 cm long, 7–10 cm wide at the base, lanceolate-attenuate, deeply channelled, dull dark green, smooth, without spots; margin reddish, with pungent deltoid reddish-brown teeth 3–5 mm long and 10–15 mm apart.
Flowers: What is remarkable about this species are its 1 or 2 candelabra-form inflorescences up to 1.25 m tall above the leaf rosette that bear 6-15 or more erect, cylindrical racemes. These are densely packed with very showy yellowish tubular buds that open to become completely overshadowed by the brilliant orange-red, 15 mm exserted stamens. Peduncle stout. The stamens give a very attractive effect. The orange-yellow opening to lemon-yellow perianth has an cylindrical-ellipsoid tube 18–20 mm long, approx 4 mm in diameter across the ovary, widening to 7 mm at the middle and narrowing slightly toward the mouth, with overlapping segments spreading only at the tips Three outer lobes swollen at the base. Ovary somewhat 3-angled. Anthers orange, stigma orange.
Blooming season: Blooms later than most aloes.
Fruits: Capsules

Notes: This species resembles the related A. thraskii and A. excelsa, which also produce rather top-heavy rosettes atop stems clothed in their upper part with a skirt of persistent dried leaves. The racemes of A. excelsa are sloping and the plant is more common. A. thraskii has leaves that are more strongly recurved.