Psychotria suber was named by Fanie Venter and the author in 2021 in Flowering Plants of Africa.  The specific epithet, suber, is Latin and means ‘corky’. This is in reference to the thick and corky bark of the stems and branches, which is distinct and distinguishes it from all the other species of Psychotria.

The author first came across this small, distinctive tree on 7 May in 1975 on the Uitkyk Road, about 14 km east of Mbombela (formerly Nelspruit) on a farm, at the time belonging to Mrs Nel. He found the shrubs growing among granite rocks, in full sun, on the highest point on the farm. Some of the reddish fruits  were collected and grown on at the Lowveld National Botanical Garden. It had been collected several times earlier by several botanist including Elize Buitendach, who collected plants at their farm Uitkyk. At the time, the author was working in the Lowveld National Botanical Garden at Nelspruit (1974-1976), and was privileged to have the experienced botanist Mrs Elize Buitendach as his mentor. Seed was sown at Kirstenbosch in 1977, they germinated well and specimens were planted in the bed at the bottom of the main lawn, opposite the lower restaurant, where they can be viewed. Plants were drawn by botanical artist Marieta Visagie (see Fig. 2).

Fig. 6. Psychotria suber growing in Kirstenbosch National Botanical Garden.

The genus Psychotria was named by Linnaeus in his Species Plantarum in 1753. It is a large group with about 1 858 species, of which most are tropical. Most species are confined to South America (Christenhusz et al. 2018). Psychotria is derived from psyche, meaning ‘life’, and pertaining to the healing properties of some species (Clarke & Charters 2016). The hallucinogenic drug ayahuasca, which is used in South America and elsewhere, is derived from Psychotria viridis and other plants. Yohimbe, a popular traditional medicine in West Africa is derived from the bark of Pausinystalia johimbe. Ipecac, a powerful emetic, comes from the roots of Carapichea ipecacuanha.

There are 5 Psychotria species recorded for southern Africa. P. suber is immediately distinguished by its corky bark, the larger, rounded, thickly leathery leaves and larger flowers. P. suber was previously confused with P. capensis (black bird-berry), which is a shrub or small tree of the forest and forest margin of eastern South Africa. These two species can be distinguished as follows:
P. suber has thick corky bark, leaves are thickly leathery, flowers are larger (10-12 mm diameter and 6 mm long), pedicel is longer (4-5 mm long) and the fruits are larger (8-9 mm diameter) where P. capensis lacks corky bark, leaves are thinly leathery, flowers are smaller (4-5 mm in diameter and 1.5-3mm long), the pedicel is shorter (0-2 mm long) and the fruits are smaller (5-6.5 mm diameter).

Fig. 7. A branch of Psychotria suber showing the leathery leaves and immature green fruits.

Psychotria suber belongs to the family Rubiaceae, a large family with about 13 620 species ranging from small herbs, epiphytes, to large trees (Christenhusz et al. 2017). In fact, most trees species in South Africa belongs to the family Rubiaceae (Van Wyk 2013). The family is at once distinguished by their leaves in opposite pairs (decussate) and bearing stipules between the petioles (interpetiolar) and regular flowers. Many plants within this family are useful. We grow so many beautiful shrubs and trees belonging to this family (Gardenia, Burchellia, Alberta magna, Pavetta etc.). Think of Coffee which is prepared from the seed of the coffee tree (Coffea arabica). Quinine has an antimalarial alkaloid prepared from the bark of two species (Cinchona calisaya, C. pubescens) from South America. Red dye is also obtained from Rubia tinctorum. The name Rubiaceae, is derived from the genus Rubia, which is derived from the Latin ruber, meaning ‘red’  (Clark & Charters 2016).

Fig. 8. A young branch of Psychotria suber showing the corky layer articulated at the nodes.