Thesium ussanguense Engl.

Perennial herb; rootstock thickened at the crown, up 4 cm across, often 2–several-fid and with short rhizomes, covered with very many conspicuous vegetative buds 5–10 mm long bearing straw-coloured scarious scales 2–6 mm long; flowering stems elongating from the buds, numerous, erect, forming tufts, 10–30 cm tall, simple to sparingly branched, the branches virgate, sharply ascending, closely leafy, often nearly the whole stem floriferous; ribs strongly raised and terminating in midrib of leaves and bracts.. Leaves at extreme base of stem reduced to scales, straw-coloured, lanceolate-subulate, ± 4–8x1–2 mm; developed leaves green or grey-green, sharply ascending, lower ones often incurved, linear-lanceolate to linear, 5–15x1–1.6 mm, acuminate, apiculate, margins cartilaginous, pale, sometimes minutely ciliolate near base, outer surface keeled by strongly raised midrib.. Flowers solitary, sessile in the axil of each bract, (10–)20–70 in long crowded spikes often with a long leafy sterile tip; bracts leaf-like, ± 4.5–11x0.8–2.4 mm; bracteoles 2, similar to bracts but often smaller, particularly narrower.. Perianth pale greenish or creamy yellow outside, white inside; tube 1–2 mm long, external glands conspicuous, ellipsoid; lobes oblong, 2–4.5 mm long, ± obtuse, margins inflexed, densely fringed with long white hairs.. Stamens inserted on lower part of perianth lobes; filaments 1–2 mm long, conspicuous; anthers 0.6–0.8 mm long.. Style 2.5–5.5 mm long; stigma nearly reaching top of perianth lobes.. Fruit pallid, ovoid-globose or ellipsoid-globose, 3–3.5 mm long, 2.5–3 mm in diameter, ribs and reticulations moderately raised.. Fig. 1/6, 7 (page 4).