Aloe hardyi

Glen

Family : Aloaceae
Common name : Penge Aloe

Aloe hardyi in conservatory at Kirstenbosch

Aloe hardyi is a decorative pendent aloe with grey-green soft leaves in rosettes at the end of hanging stems. It is confined to the Olifants River valley in Mpumalanga where it can be seen on dolomite rock faces in warm dry savanna.

Description
Aloe hardyi is a fast growing aloe forming solitary rosettes hanging from cliff faces. Its roots are cylindrial and up to 6 mm in diameter and form a network which anchors the plant in crevices on cliffs. The stems are simple or occasionally branched from the base to form loose hanging leaf clusters with stems up to 1,5 m long. The leaves are pendulous or curve downwards, and are borne in dense rosettes, up to 400-700 mm long and 50-80 mm in diameter, at the ends of branches. During the rainy season the leaves spread slightly and curve inwards, but during the dry season they draw together again. The skin (epidermis) of the leaves is bluish to pale green with a powdery bloom and with a reddish colour during the dry season or during prolonged droughts. The leaves on young plants are distichous (regularly arranged one above the other in two opposite rows, one on each side of the stem) for the first two years. The inflorescence is a simple raceme 450-700 mm long in total. At first it hangs but then curves upwards so that the flower-bearing part, which is up to 200 mm long and conical in the bud stage, stands almost upright. The flowers are spreading to sub-pendulous, with orange-red, green-tipped tepals 25-40 x 7 mm. The fruiting capsule is ascending-spreading and 25 x 7 mm. The seeds are angular, 3 ´ 2 mm and grey, and there are about 55-70 per capsule.

Inflorescence

Flowering time
Flowering occurs mainly during midwinter (July, southern hemisphere).

Status
Aloe hardyi is rare and is confined to the Olifants River Valley. However it is not threatened due to its safe cliff habitat.

Distribution and Habitat
Aloe hardyi is a dolomite endemic, confined to the Olifants River Valley between the Strydom tunnel and Penge asbestos mine in the Limpopo Province and adjacent territory where the same geological formation occurs. Its habitat consists of vertical cliffs, up to about 500 m high, on exposed N and NW aspects but also on southern and eastern slopes. The temperature can be extremely high, especially on north-facing aspects during summer (35-45ºC). Temperatures on the shadier south-facing lopes are lower. Winters are cool to cold but frost is absent. Rain falls mainly during summer and ranges between 300 and 400 mm per annum (with thunder showers mainly from October to May). The vegetation consists of Poung Dolomite Mountain Bushveld of the Savanna Biome (Mucina et al. 2005). Aloe hardyi shares its habitat with other plant species such as Sterculia rogersiae, Aloe sessiliflora, Euphorbia lydenburgensis, E. tirucallii, Sarcostemma viminale, Commiphora marlothii, Ficus abutilifolia and a species of Vellozia. The geology consists of dolomite of the Chuniespoort Formation, Malmani subgroup (Transvaal Supergroup).

Seeds are dispersed by wind during early spring (end of September), just before the spring rains.

Derivation of name and historical aspects
Named by Dr Hugh Glen after Mr. Dave Spencer Hardy (1931-1998) horticulturist at the former Botanical Research Institute and responsible for building up a considerable collection of succulent plants from South Africa and Madagascar (Gunn & Codd, 1981).

Aloe hardyi is related to Aloe arborescens, at once distinguished by its flaccid drooping stems. Its juvenile leaves remain distichous for at least two years whilst in Aloe arborescens they form a spiral in the first year. Aloe arborescens is a sturdy shrub up to 1,5 m tall.

Ecology
Aloe hardyi is pollinated by sunbirds.

Uses and cultural aspects
No uses have been recorded.

In conservatory at Kirstenbosch 

Growing Aloe hardyi

Propagation
Aloe hardyi is easily propagated from seed sown in spring or summer time. It is recommended to add a fungicide when watering. The plants grow fast and can reach flowering stage in 3 years. They are best sown in a sandy, well-drained potting soil in a warm shady position in standard seed trays. Germination will take place within 3 weeks and the seedlings grow fast. Cover with a thin layer of sand (1-2 mm) and keep moist. The seedlings can be planted out in individual bags or containers as soon as they are large enough to handle.

Cultivation
Aloe hardyi thrives in warm dry gardens and also as a pot or container plant. It prefers full sun and a steep slope which provides sufficient growing space. Plants will benefit from compost or any organic feeding. Although the plants are not frost-tolerant they can survive light frost. Aloe hardyi thrives in a wide range of soil but prefers alkaline soil. It is fairly pest-free, but may occasionally get attacked by the Aloe snout weevil. Over-watering will lead to fungal infection in the crown, resulting in rot.

References

  • Glen, H. 1986. Aloe hardyi. Flowering plants of Africa. Plate 1942.
  • Muchina, L., Rutherford, M. C., Powrie, L. W. 2005. Vegetation map of South Africa, Lesotho and Swaziland. SANBI.
  • Reynolds, G.W. 1974. The aloes of South Africa. A.A. Balkema, Cape Town, Rotterdam.
  • Van Wyk, B-E., & Smith, G. D. 1996. Guide to the aloes of South Africa. Briza, Pretoria.
  • Gunn, M. & Codd, L.E. 1981. Botanical exploration of Southern Africa. Botanical Research Institute. A.A. Balkema, Cape Town.

 

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