Tavaresia barklyi
(T.-Dyer) N.E. Br.

Family: Apocynaceae
Common names:
Devil's trumpet (E); bergghaap, katstert (A); olukatai (Ndonga Ovamboland, northern Namibia); okukato lekadi, olukato lendume (Kwanyama Ovamboland, northen Namibia)

Tavaresia flower Photo: L. Viljoen

The neat appearance of the ribbed stems furnished with bristles at first reminds one of a cactus, but when the bizarre trumpet-shaped flowers appear, one realizes that it is not. Large trumpet (tubular) flowers are characteristic of the genus and the many-ribbed stems for the species. Growing this fascinating species may be a challenge for the collector.

Description
Succulent herb with cylindrical, 1012 ribbed, blue-green stems. The flowers are large and showy, tubular to trumpet-shaped, and range from 35100 mm long and ± 25 mm in diameter, arising at the base of the stems. One to four flowers per inflorescence open successively. Flowers are pale yellow to cream to flesh-coloured with dark red spots and streaks on the outside, darker on the inside becoming almost fully maroon to purple at the base inside.

Tavaresia angolensis tubular flowers Tavaresia flower inside
Tavaresia angolensis tubular flowers
Tavaresia flower inside

The stems are erect, 4060 mm long and ± 15 mm in diameter, many angled covered by tubercles that are tipped by three sharp bristles. The plants bloom in midsummer (November to April), usually after rains. It is reported that when the stem is injured or crushed it emits a strange musty odour. The fruit consists of elongated follicles which house the seeds. When the follicles are fully-matured they burst open to release the seeds, each of which has a tuft of hair.

Tavaresia barklyi stem Tavaresia angolensis fruit follicles
Tavaresia barklyi stem
Tavaresia angolensis fruit follicles

Conservation status
Although this species has a wide distribution range, it is seldom abundant in local populations. According to the latest assessment the bergghaap is listed as Least Concerned in South Africa (2009) and not listed in the Red Data Book of Namibian Plants (2005). It is, however, protected under the Limpopo Environmental Management Act 2003 in the Limpopo Province (South Africa).

Distribution and habitat
Tavaresia barklyi is widely distributed in southern Africa, reported for Angola, Botswana, South Africa (Free State, Limpopo and Northern Cape Provinces), Namibia and Zimbabwe. Plants grow on rocky outcrops and slopes and in sandy soils on plains, usually in somewhat protected situations, in full sun or light shade.

Derivation of name and historical aspects
The genus currently consists of three species: T. barklyi, T. angolensis and T. thompsoniorum distributed in southern and tropical Africa.

Tavaresia hybridises easily and a hybrid between T. barklyi and Stapelia gigantea has been described previously as T. meintjiesii. Some taxonomists are of the opinion that T. thompsoniorum may also be of hybrid origin.

In the genus the outer corona consists of lobes that are basally fused becoming threadlike and ending at the tips in a spherical knob.

T. angolensis and T. barklyi are distinguished in that the first has 59 ribs on the stem and the latter 814. These two species are distinguished from T. thompsoniorum by the size of the tube, shape of the lobes and colouring of the flowers that are different.

The genus was established in 1854 by Welwitsch, an Austrian botanist, based on plants collected from Angola. He dedicated the genus to Josè Tavares de Maçedo, an official in the Portuguese ministry of Marine and the Colonies. The specific epithet honours Sir Henry Barkly (18151898) who collected it in 1871 and was Governor of the Cape in 18701877.

At one stage the species was placed in the genus Decabelone that literally means ten prickles. It was later found that the species from Angola had priority under the ICBN (International Code of Botanical Nomenclature) and the generic name Tavaresia was re-introduced by N.E. Brown in Flora Capensis in 1909. When two taxa (the same species) are described validly by different people (usually in different publications) the older of the names is accepted according to the rules of the ICBN. This is why the name Tavaresia is used instead of Decabelone. The interesting history on the usage of the generic name Tavaresia versus Decabelone is fully discussed by Leach (1993).

The long tubular flowers immediately distinguish this species from any other known stapeliad in southern Africa.

Ecology
The tubular flowers and intricate fertile parts indicate a plant adapted to specific pollinators. Plants are insect pollinated. Thus far, to my knowledge, the specific pollinators have not been recorded. This may be an interesting topic for further research; specifically to determine whether the large-and-small-flowered forms are pollinated by different insects or not. These two forms were formally known as two distinct species (T. barklyi and T. grandiflora).

The seed are released from the fruit when they split open. As the tuft of hair (coma) dries out on the tip of the seed it unfolds into a parachute-like structure that carries the seed off in the slightest breeze. The wind distribution of the seeds probably explains the wide spatial distribution of plants in a community. After a time the coma detaches and if the seed lands in a suitable place it will germinate and establish a new plant.

Uses and cultural aspects
The bergghaap is mainly grown by plant collectors, lovers of succulents and enthusiasts who enjoy growing unorthodox looking plants.

Except for its horticultural use, not much is known about other uses. It has been reported that the plant is crushed and externally applied to painful and aching parts of the body as a kind of dressing to alleviate pain.

It has also been reported that the stems are chewed, possibly for nourishment or to obtain fluids. First the outer skin of the stems is pealed and then it is chewed, in the same way as Hoodia is widely used. It has, however, not been established that Tavaresia acts as an appetite suppressant.

Tavaresia plant

Growing Tavaresia barklyi

Tavaresia may be a good indigenous substitute for any exotic cactus that is grown in a container on a veranda or window sill. Even when not in flower they are interesting.

Throughout its range, the species grow naturally in situations of light shade, sandy soils and high temperatures in areas that receive summer rainfall never in areas that are prone to frost and low winter temperatures. It would be well suited for cultivation in the north and north-western provinces in South Africa. In areas that have mild winters and receive infrequent frost it may do well as a container or indoor plant. Success in growing the plant could easily be achieved when these natural growing conditions are successfully simulated.

The devil's trumpet can be cultivated reasonably easily when kept relatively dry in cold and wet conditions. Where rot does occur, it is advised to graft the healthy parts onto any strongly -rooted Stapelia. Tavaresia are easily propagated by stem cuttings or seed. This katstert is easily grown from fresh seed, but it is less easy to keep plants healthy.

Growing from seed:
Seeds take about a year to ripen, but germinate rapidly after sowing the fresher the seeds the better. Sow seed in spring in a well-drained, light, sandy soil mixed with compost and cover with a thin layer of soil. The pH should be 6.57.5. Keep the temperature at 2535°C, in a shaded and fairly moist position.

Once the seedlings have germinated and are about 5 cm high, they can be pricked out and planted (be careful not to damage the roots when pricking out!). Generally the plants grow fast and most will flower within two to three years when grown from seed.

Growing from cuttings:
Cuttings should be taken during the active growing stage to ensure good rooting, before the plants enter their dormant phase. Cuttings can flower in their first year, depending on the size of the cutting. Travaresias grow easily from cuttings as long as they are given adequate time to dry out before planting (at least two weeks). Leave the cuttings in the shade to dry out. Use a fungicide drench before planting. Place them in a well-ventilated area with about 40% shade. Water daily during very hot weather. Plants that do not grow well from cuttings can also be propagated by grafting.

Cultivation:
Keep plants well ventilated and in good light to prevent damping off. Feed once in the growing season (summer) with a fertilizer (Seagro or Bounceback). The soil should drain well: equal parts of washed river sand, potting soil and topsoil is recommended. It is important to keep the plants dry during the winter otherwise they rot easily. Plants prefer warm but dry atmospheres in well-drained soils. They grow in full sun or semi-shade and are totally frost-intolerant.

Pests & diseases:
Plants are susceptible to black rot (bacterial infections) and seedlings to damping-off (Pythium infection). Treat the seedling medium with a fungicide, but bear in mind that some chemicals may stunt their growth. The devil's trumpet is extremely susceptible to rot that is caused by the roots being infested with woolly aphids.

Woolly aphids on the roots and underground stems and mealy bugs on the stems and bases are the most common problems. A strong jet of water or a 50/50 mix of methylated spirits and water can be used to eradicate these pests. Black rot, a secondary infection after woolly aphid attacks, is also problematic. Remove all traces of black rot with a sterile knife, spray the plant with Benelate and dust with flowers of sulphur. As soon as stem rot is noticed, the affected parts should immediately be cut away and destroyed.

References and further reading

  • Barkhuizen, B.P. 1978. Succulents of South Africa. Prunell, Cape Town.
  • Bruyns, P.V. 2005. Stapeliads of southern Africa and Madagascar. Vol. II. Umdaus Press, Hatfield.
  • Court, D. 2000. Succulent flora of southern Africa. A.A. Balkema, Rotterdam.
  • Downs, P.E. 1999. Tavaresia angolensis. Asklepios 76: 1112.
  • Dyer, R.A. 1964. Decabelone meintjesii. The Flowering Plants of Africa 36: t.1420.
  • Germishuizen, G. & Fabian, A. 1997. Wildflowers of northern South Africa. Fernwood Press, Vlaeberg.
  • Hardy, D. & Fabian, A. 1992. Succulents of the Transvaal. Southern Book Publishers, Halfway House.
  • Hargreaves, B.J. 1990. The succulents of Bostwana. Government Printer, Gabarone.
  • Leach, L.C. 1993. Tavaresia versus Decabelone (Asclepiadaceae). Taxon 42: 665667.
  • Leistner, O.A. (ed.). 2000. Seeds plants of southern Africa: families and genera. Strelitzia 10. National Botanical Institute, Pretoria.
  • Loots, S. 2005. Red Data Book of Namibian Plants. South African Botanical Diversity Network Report No. 38. SABONET, Pretoria and Windhoek.
  • Pole-Evans, I.B. 1932. Tavaresia barklyi. The Flowering Plants of South Africa 12: t.475.
  • Raimondo, D., Von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. & Manyama, P.A. 2009. Red List of South African plants 2009. Strelitzia 25. South African National Biodiversity Institute, Pretoria.
  • Oliver, I.B. 1998. Grow succulents. Kirstenbosch Gardening Series. National Botanical Institute, Cape Town.
  • Smith, C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35.
  • Van der Walt, R. 2009. Wild flowers of the Limpopo Valley. Published by Retha van der Walt, Musina.
  • Van Jaarsveld, E. & Nagel, R. 1999. Tavaresia thompsonii Van Jaarsveld & Nagel, a new species from S. Angola. Asklepios 76: 910.
  • Van Koenen, E. 2001. Medicinal, poisenous and edible plants in Namibia. Klaus Hess Publishers, Windhoek.

 

 

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