Aloe nubigena

Groenew.

Family : Asphodelaceae
Common names : Graskop cliff aloe (Eng.), Graskop krans-aalwyn (Afr.).

Aloe nubigena is an attractive small aloe with soft, strap-shaped leaves and is ideal for growing in hanging baskets.

Description
Aloe nubigena is small, soft-leaved and medium to fast-growing. The plants proliferate from the base forming small clusters, usually hanging from cliffs. The stems are horizontal to drooping (pendulous), up to 100 mm long and covered with old dry leaf remains. The green functional leaves are produced in an apical rosette, often borne in two opposite rows (distichous). They are linear and pendulous and are up to 600 mm long and 20 mm in diameter. The leaf margins are entire or sometimes beset with very small soft teeth (denticulate) in some populations. The leaf surface is green and smooth. The inflorescence consists of a simple spreading to spreading-pendulous raceme up to 210 mm long. The flowers are tubular (27 × 7 mm), drooping, orange-red in colour with green tips and are borne on pedicels about 30 mm long. The fruit is an oblong-conical capsule 20 × 10 mm. The seeds are angular, 3 × 1,5 mm and dark brown. Aloe nubigena is one of the 24 grass aloe species confined to South Africa.

A close-up of a young plant of Aloe nubigena on Mariepskop. Note the moss.

Conservation status
Aloe nubigena is a rare species confined to cliffs on the north-eastern Drakensberg escarpment north of Graskop in Mpumalanga. The plants grow in inaccessible sites on sheer precipices and are thus well protected. The species is also well established in cultivation (ex situ conservation) and is grown by succulent plant lovers all over the world.

The habitat of Aloe nubigena at Graskop in Mpumalanga. Plants grow on sheer cliffsDistribution and habitat
Aloe nubigena is confined to vertical quartzitic sandstone cliffs on the upper eastern escarpment. The average daily maximum of the area is about 20°C and the average daily minimum about 5°C. The temperature is cool throughout the year with frequent fog during the summer rainy season. The rainfall is high, occurs mainly during summer and ranges between 1500 and 2000 mm per annum. Plants grow at an altitude of 1450–2100 m above sea level. Associated vegetation includes the Northern Escarpment Quartzite Sourveld of the Grassland Biome (Mucina et al., 2005). Associated plants in its native habitat include Crassula pellucida subsp. alsinoides, Aloe arborescens, Drimia robusta, Scilla natalensis and various moss species. The geology consists of quartzitic sandstone (Black reef formation, Transvaal Supergroup).

Derivation of name and historical aspects
The specific name “nubigena” = “cloud born” pertains to its habitat which is frequently covered in fog. Aloe nubigena was first collected by Dr F.Z. van der Merwe (inspector of schools at the time) near Graskop in 1935 and named by Mr H.B. Groenewald in 1936 in the Afrikaans journal “Tydskrif vir Wetenskap en Kuns”.

Ecology
Aloe nubigena flowers mainly during summer (November–April) but sporadically at other times. Plants are pollinated by sunbirds and seeds are wind-dispersed. The plants grow on quartztic sandstone ledges in full sun or partial shade. Initially plants are solitary but proliferate later to form small to dense clusters.

Uses and cultural aspects
It is popular in cultivation, but no medicinal properties have been reported.

A close-up of Aloe nubigena in its habitat at God's Window near Graskop on the Mpumalanga escarpment

Growing Aloe nubigena

Aloe nubigena is easily grown from offhoots or by division. Cuttings are grown in sand or a mixture of sand and slightly acid peat. They grow fairly fast and soon form small clusters. Away from its habitat, it is best grown as a pot plant or in a hanging basket in a greenhouse and kept moist and cool during the summer months. Feed during spring and summer.

References and suggested reading

  • Glen, H.F. & Hardy, D.S. 2000. Aloe nubigena Groenwald in Aloaceae (first part). Flora of Southern Africa. Volume 5, part 1. National Botanical Institute, Pretoria 2000.
  • Mucina, L. & Rutherford, M. C. (Eds.) 2006. The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National Biodiversity Institute, Pretoria.
  • Reynolds, G.W. 1974. The Aloes of South Africa. A.A. Balkema, Cape Town, Rotterdam.
  • Van Wyk, B.-E. & Smith, G.F. 1996. Guide to the Aloes of South Africa. Briza Publications, Pretoria.

 

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