Pausinystalia macroceras (PROTA)
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Introduction |
| General importance |  
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| Geographic coverage Africa |
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| Geographic coverage World |
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| Medicinal |
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| Timber |
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| Fuel |
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Pausinystalia macroceras (K.Schum.) Pierre
- Protologue: Act. Soc. Linn. Bordeaux 61: 130 (1906).
- Family: Rubiaceae
Vernacular names
- False johimbe (En).
Origin and geographic distribution
Pausinystalia macroceras is distributed from Nigeria eastward to DR Congo and southward to Cabinda (Angola).
Uses
The wood is valued for furniture and cabinet work. In Cabinda (Angola) it is used for house construction and flooring. The wood is suitable for joinery, interior trim, ship building, vehicle bodies, ladders, sporting goods, toys, novelties, agricultural implements, handles, musical instruments, boxes, crates, precision equipment, matches, carvings, turnery, pattern making, veneer and plywood. In Nigeria it is used as fuelwood.
The bark is widely used as an aphrodisiac and stimulant. In Cameroon, for instance, the pulverized bark is eaten against sexual weakness. In Congo the bark is used to stave off sleep, and sap from the bark is applied in an enema as a vermifuge and topically for the treatment of ringworm and other fungal skin infections.
Properties
The heartwood is pale yellow to pale pink, with irregular stripes occasionally present; it is not clearly demarcated from the sapwood. The grain is straight, texture fine and even. The wood is lustrous and contains a reddish brown gum.
The wood is medium-weight, with a density of about 700 kg/m³ at 12% moisture content. It air dries rapidly without serious deformation. The rates of shrinkage are rather high, from green to oven dry 4.7% radial and 10.7% tangential. Once dry, the wood is moderately stable in service. At 12% moisture content, the modulus of rupture is 151 N/mm², modulus of elasticity 10,900 N/mm², compression parallel to grain 65 N/mm², shear 8 N/mm², cleavage 12.5 N/mm and Chalais-Meudon side hardness 3.8.
The wood saws well, works easily with all tools, planes to a smooth surface, and finishes well. It takes and holds nails and screws well, and glues satisfactorily. The peeling properties are good, but splitting of veneer may occur during drying. For slicing, radial sections are recommended to reduce defects caused by the rather high shrinkage rates.
The durability of the wood is classified as moderate, although it is not susceptible to attacks by termites and marine borers. The sapwood is not susceptible to Lyctus borer attack. The heartwood is resistant to impregnation with preservatives, the sapwood moderately resistant.
The bark contains the indole alkaloid yohimbine, but in smaller quantities than in the bark of Pausinystalia johimbe (K.Schum.) Pierre ex Beille, which has led to Pausinystalia macroceras sometimes being called ‘false yohimbe’. The bark has been recorded to contain only 0.02–0.32% indole alkaloids and more of the inactive alkaloid yohimbinine than of yohimbine. However, bark from Congo was found to contain 4% alkaloids, of which 60–65% yohimbine. Other alkaloids isolated from this bark were corynanthidine (α-yohimbine), β-yohimbine, ajmalicine, corynanthine, and the levo-rotatory isomer of calycanthine.
The bark also contains saponins and tannins. Methanolic extracts of the stem bark have shown in-vivo anti-ulcerogenic, antidiarrhoeal, analgesic and anti-inflammatory effects in rats.
Description
- Evergreen, medium-sized to fairly large tree up to 40 m tall; bole branchless for up to 18 m, straight, cylindrical, up to 90 cm in diameter, without buttresses, but with grooved base; bark surface often fissured, grey to brown, inner bark fibrous, creamy white, turning reddish brown upon exposure.
- Leaves decussately opposite, simple and entire; stipules caducous; petiole (3–)7–25 mm long; blade obovate to elliptical, 6.5–47 cm × 2.5–17.5 cm, base cuneate to rounded, apex short-acuminate, papery or thinly leathery, glabrous, pinnately veined with 5–16 pairs of lateral veins.
- Inflorescence an axillary panicle, 9–15 cm × 5–14 cm, with flowers in clusters at the ends of branches.
- Flowers bisexual, regular, (4–)5–6-merous, fragrant; pedicel up to 0.5 mm long; calyx with short tube up to 0.5 mm long and triangular to rounded lobes 0.5–1 mm long, acute, glabrous or somewhat hairy outside, densely hairy inside; corolla white, sometimes pink, glabrous outside, hairy inside, tube with basal narrow part 0.5–1 mm long and apical bladder 1–2 mm long, lobes erect, each with a linear appendage 6–12.5 mm long; stamens attached at base of the corolla bladder, alternating with the lobes, sessile; ovary inferior, 2-celled, glabrous, style 1–2 mm long, stigma 2-lobed.
- Fruit an oblong, compressed capsule, 10–20 mm × 5–7 mm, 4-valved, many-seeded.
- Seeds 5–14 mm × 1–2 mm, winged.
Other botanical information
In Nigeria Pausinystalia macroceras flowers in May–September, and fruits in January–March.
Pausinystalia comprises 5 species, and occurs in West and Central Africa. It is closely related to Corynanthe. Pausinystalia macroceras can be distinguished from Pausinystalia johimbe by its smaller leaves with longer petioles. Furthermore, the bark of Pausinystalia johimbe is tasting extremely bitter and is easy to peel off, whereas that of Pausinystalia macroceras is less bitter and difficult to peel off. Differences in slash characteristics, often mentioned as being distinguishing, are not reliable.
Ecology
Pausinystalia macroceras occurs in lowland evergreen forest, primary as well as secondary, and also in gallery forest.
Genetic resources
In view of its fairly wide distribution and local abundance, it is unlikely that Pausinystalia macroceras is threatened with genetic erosion.
Prospects
Although the wood is recorded to be suitable for a wide range of purposes, evidence of its use is scarce. Its role as a timber is unlikely to become more important in the future. The bark of Pausinystalia macroceras is used as an aphrodisiac and stimulant as a substitute or adulterant of that of Pausinystalia johimbe, but contains lower amounts of the main active compound (yohimbine).
Major references
- Bolza, E. & Keating, W.G., 1972. African timbers: the properties, uses and characteristics of 700 species. Division of Building Research, CSIRO, Melbourne, Australia. 710 pp.
- Burkill, H.M., 1997. The useful plants of West Tropical Africa. 2nd Edition. Volume 4, Families M–R. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 969 pp.
- Leboeuf, M., Cavé, A., Mangeney, P. & Bouquet, A., 1981. Alkaloids of Pausinystalia macroceras. Planta Medica 41(4): 374–378.
- Stoffelen, P., Robbrecht, E. & Smets, E., 1996. A revision of Corynanthe and Pausinystalia (African Rubiaceae - Coptosapelteae). Botanical Journal of the Linnean Society 120(4): 287–326.
- Sunderland, T.C.H., Cunningham, A.B., Tchoundjeu, Z., Ngo-Mpeck, M.-L. & Lairs, S.A., 2004. Yohimbe (Pausinystalia johimbe). In: Clark, L.E. & Sunderland, T.C.H. (Editors). The key non timber products of Central Africa: state of the knowledge. Technical paper No 122. Office of Sustainable Development, Bureau for Africa, United States Agency for International Development, Washington DC, United States. pp. 121–140.
Other references
- Hallé, N., 1966. Rubiacées (1re partie). Flore du Gabon. Volume 12. Muséum National d’Histoire Naturelle, Paris, France. 278 pp.
- Ihenyen, J., Okoegwale, E.E. & Mensah, J.K., 2009. Forest products of Ehor Forest Reserve in Uhunmwode local government area, Edo State. Researcher 1(4): 83–91.
- Keay, R.W.J., 1989. Trees of Nigeria. A revised version of Nigerian trees (1960, 1964) by Keay, R.W.J., Onochie, C.F.A. & Stanfield, D.P. Clarendon Press, Oxford, United Kingdom. 476 pp.
- Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
- Nwafor, P.A., Jacks, T.W. & Ekanem, A.U., 2007. Analgesic and anti-inflammatory effects of methanolic extract of Pausinystalia macroceras stem-bark in rodents. International Journal of Pharmacology 3(1): 86–90.
- Nwafor, P.A., Jacks, T.W., Ekanem, A.U. & Poh, C.F., 2005. Antiulcerogenic and antidiarrhoeal potentials of methanolic extract of Pausinystalia macroceras stem-bark in rats. Nigerian Journal of Natural Products and Medicine 9: 63–67.
- Sallenave, P., 1964. Propriétés physiques et mécaniques des bois tropicaux. Premier supplément. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 79 pp.
- Sunderland, T.C.H., Ngo-Mpeck, M.-L., Tchoundjeu, Z. & Akoa, A., 1999. The ecology and sustainability of Pausinystalia johimbe: an over-exploited medicinal plant of the forests of Central Africa. In: Sunderland, T.C.H., Clark, L.E. & Vantomme, P. (Editors). Non-wood forest products of Central Africa: current research issues and prospects for conservation and development. FAO, Rome, Italy. pp. 67–77.
- Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.
- Vivien, J. & Faure, J.J., 1985. Arbres des forêts denses d’Afrique Centrale. Agence de Coopération Culturelle et Technique, Paris, France. 565 pp.
Author(s)
- M. Brink, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
Correct citation of this article
Brink, M., 2012. Pausinystalia macroceras (K.Schum.) Pierre ex Beille. In: Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 17 September 2026.
- See the Prota4U database.