Swertia usambarensis Engl.

Annual herb without basal leaf rosette.. Stems erect, 25–50 cm long, unbranched or branched, stem angles smooth.. Leaves sessile or shortly petiolate, blade oblong-lanceolate, linear-lanceolate or ovate-lanceolate, 25–40 mm long, 5–15 mm wide, obtuse or subacute, narrowed at the base.. Inflorescences corymb-like, partial inflorescences many, each 5–6(–7)-flowered; pedicels 7–32 mm long, pedicel of the terminal flower always shorter than pedicels of lateral flowers; bracteoles oblong-lanceolate, linear-lanceolate or ovate-lanceolate, 1–1.6 mm long, 0.4–0.6 mm wide, obtuse or subacute.. Flowers 5-merous.. Calyx lobes: 3 longer and wider than others, oblong-lanceolate, lanceolate or linear-lanceolate, 6–9 mm long, 1.5–2.5 mm wide, acute.. Corolla white, sometimes with purplish-brown median dorsal stripes outside; tube very short, 0.4–1.1 mm long; lobes oblong-elliptic or obovate-elliptic, 6–12.5 mm long, 4–7 mm wide, obtuse or acute; nectaries 2 per lobe, yellow, circular, 0.4–1.2 mm diameter, 0.2–0.6 mm apart, 1.8–2.3 mm from base of lobes, margin fimbriate, fimbriae 1.1–2.8 mm long.. Stamens with filaments 4–7 mm long, scale-like projections present at their point of attachment to the corolla lobes; anthers oblong, 1–2.1 mm long.. Ovary oblong, 4.5–7.5 mm long, 1–3 mm diameter; style obsolete; stigma bilobed, lobes 0.5–0.9 mm long, 1–1.6 mm wide, obtuse, forming a crescent-shaped rim on the capsule valves; parietal placentae conspicuous.. Capsule oblong, 8–11 mm long, 4–5 mm diameter.. Seeds light brown, 0.4–0.5 mm in diameter, surface with wavy ridges.