Dicerothamnus is a genus of flowering plants in the daisy family, Asteraceae (order Asterales, tribe Gnaphalieae), formally and validly described by M. Koekemoer in 2019 (Phytotaxa 403(4): 254). GBIF's taxonomic backbone recognizes two accepted species, D. rhinocerotis and D. adpressus, though the genus is dominated in practice by its well-known type species, Dicerothamnus rhinocerotis — known as "renosterbos" or "rhinoceros bush" in South Africa.
The species has a layered taxonomic history: it was first described as Stoebe rhinocerotis by Carl von Linné filius in 1781, moved to the genus Elytropappus by Lessing in 1832, and only transferred to the newly erected genus Dicerothamnus once that name was validly published in 2019 — for decades before that the combination "Dicerothamnus rhinocerotis" circulated informally without formal standing.
Morphologically, the type species is a single-stemmed shrub to about 2 m, with gnarled grey bark on old wood and whip-like young twigs densely set with tiny triangular leaves pressed to the stem; fine white hairs between the leaves give the whole plant a greyish, woolly cast. Its capitula (flowerheads) are small and inconspicuous, each holding a few tiny purple florets, and its seeds are wind-dispersed on a feathery pappus.
The genus is endemic to South Africa and is the namesake and dominant shrub of the renosterveld vegetation type, a distinctive shrubland of the Cape Floristic Region, though the plant itself ranges well beyond renosterveld proper — through Namaqualand and the Richtersveld, and east to the Great Escarpment near Molteno and to East London in the Eastern Cape. Ecologically it is a deep-taprooted, fire-killed, seed-regenerating shrub that is unpalatable to livestock and has consequently spread on overgrazed and disturbed land; it supports a specialist herbivore, the flightless renosterbos locust (Lentula obtusifrons). Historically its branch tips have been used in traditional Cape medicine (typically infused in wine or brandy) for stomach complaints, while farmers have long regarded it as a problematic weed of grazing land.
Distribution
Endemic to South Africa. Widespread across the Cape Floristic Region and Namaqualand, north to the Richtersveld, and east along the Great Escarpment to Molteno and East London in the Eastern Cape. The renosterveld vegetation type it typifies is itself confined to the winter-rainfall South-Western Cape, but the plant ranges well beyond it, including into Namibia.
Ecology
A deep-taprooted (6+ m) shrub able to exploit arid soils via groundwater access. It is flammable and killed by fire, regenerating entirely from a large, dormant, wind-dispersed seed bank; seedlings need disturbance to establish but are highly sensitive to drought and shade until the taproot develops. Apparently wind-pollinated and largely outcrossing. Unpalatable to livestock, it has spread under grazing pressure, and supports a specialist flightless herbivore, the renosterbos locust (Lentula obtusifrons), along with gall-forming scale insects and other minor associates.
Cultivation
Not a mainstream horticultural subject, but grown at Kirstenbosch and in South African native, drought-tolerant, and restoration/landscaping plantings; a silvery-white cultivar/form is more often grown than the wild type. Tolerates heavy clay soils. Propagated from smoke-treated autumn-sown seed or, more reliably, from late-summer tip/heel cuttings rooted under mist and hardened off before potting. Because of its weedy tendencies, deliberate introduction outside its native range is discouraged.
Conservation
The plant itself is not considered threatened — it is weedy, widespread, and abundant on disturbed and overgrazed land — even though the renosterveld vegetation type it defines and names has been severely reduced by agriculture.
Cultural Uses
Used in traditional Cape medicine: young branch tips infused in wine or brandy (or as a powder) to treat indigestion, dyspepsia, stomach ulcers/cancer symptoms, appetite loss, children's diarrhoea, fevers and influenza; the active compound has been reported as having anti-inflammatory activity, though the plant itself is bitter, astringent and resinous. Conversely, it is regarded by farmers (especially in the Eastern Cape) as a serious agricultural weed of overgrazed land, and was mistakenly thought in the 1920s to be an introduced alien, prompting eradication and biocontrol research.
History
Described as Stoebe rhinocerotis by Carl von Linné filius in 1781, transferred to Elytropappus by Lessing in 1832, and finally moved into the newly validated genus Dicerothamnus by Koekemoer in 2019 (Phytotaxa 403(4): 254) — the combination had circulated informally for years before formal publication. The species' epithet and Afrikaans name "renosterbos" reference a historical association with the black rhinoceros at the Cape, documented in South African writings as early as 1685.
Taxonomy Notes
GBIF's backbone treats Dicerothamnus as an accepted genus of Asteraceae (order Asterales, tribe Gnaphalieae) with two accepted species, D. rhinocerotis and D. adpressus — so the genus is not strictly monotypic in the taxonomic backbone, even though only D. rhinocerotis is well documented and widely known. The genus was split off from the older, related genus Elytropappus (Cassini; name from Greek elytron "sheath" + pappos "down," referring to a cup-like rim at the pappus base), which retains 8 other Cape Floristic Region species, notably common in the Cederberg.
