Pentas arvensis Hiern

Pyrophytic herb, with 4–9 unbranched herbaceous stems (15–)30–50 cm. tall from a very woody rootstock ± 1 cm. wide, ± hairy in 2 lines, often showing signs of burning.. Leaves paired or rarely in whorls of 3; blades elliptic to lanceolate, 2.5–8 cm. long, 0.4–2.6 cm. wide, bluntly acute or obtuse at the apex, cuneate at the base, with adpressed crisped hairs on both surfaces; petiole obsolete or up to 2 mm. long; stipules with 3–5 linear or deltoid lobes 3–4(–9) mm. long from a short base.. Inflorescences trichotomous, few-many-flowered, laxly globose, each cluster 2–2.5 cm. wide.. Flowers white or less often pinkish.. Calyx-tube 1–1.25 mm. long and wide; lobes oblong, the largest up to 3 mm. long, 0.5–1 mm. wide, the rest smaller, or minute.. Long-styled flowers: corolla-tube 4.3–5(–6) mm. long, widened above to 1.5–2 mm. at the apex; lobes oblong or elliptic, 1.75–3 mm. long, 0.75–1.5 mm. wide, hairy over the basal half inside; stamens entirely included; style exserted 1 mm., stigma thickened, the lobes 1 mm. long.. Short-styled flowers similar: corolla-tube 4 mm. long; lobes 2.5–3 mm. long, 1.5 mm. wide; throat densely hairy; anthers exserted 2 mm.. Fruiting inflorescence 1.5–3 cm. wide; peduncle 6.5–10 cm. long.. Capsules subglobose, 2.5–4 mm. long, 2.5–3.5 mm. wide; beak 1.5 mm. tall.

Appearing in upland grassland after fires.