Ugutugulu Whistlesweet

Thorncroftia lotteri is a semi-succulent, erect herb or small shrub growing 30–100 cm (12–39 in) tall, usually with several main stems. The stems are grey near the base and purple to pale green above, sparingly branched, and densely covered in a felt-like layer of recurved hairs with scattered capitate glands. The leaves are opposite, ovate to elliptic-obovate, typically 3–4 cm (1.2–1.6 in) long and 2–3 cm (0.8–1.2 in) wide. The venation is sunken above and prominently raised below, forming a network of shallow recesses. Both leaf surfaces are hairy, especially the underside. The leaf margins are crenate in the upper three-quarters, with nine or more rounded scallops on each side. The leaf tip is rounded or acute, the base cuneate to obtuse, and the petiole is relatively long, usually 12–15 mm (0.47–0.59 in). The inflorescence is a compact, terminal panicle with a main axis up to 20 cm (8 in) long. The bracts are leaf-like near the base of the inflorescence and become progressively smaller towards the tip. The calyx is two-lipped and five-toothed, purple to maroon in colour, and 7–9 mm (0.28–0.35 in) long in fruit. The corolla is tubular, narrowly cylindrical, and laterally compressed, measuring about 20–23 mm (0.79–0.91 in) in length. It is light lilac, becoming paler towards the tip, and bears conspicuous glandular hairs. …

The genus Thorncroftia is named for George Thorncroft (1857‒1934), an amateur botanist who collected extensively in the Barberton area. The species is named for Dr Mervyn Lötter (b. 1972), a biodiversity planner and GIS expert at the Mpumalanga Tourism and Parks Agency, who helped collect specimens of the plant.