Branched or unbranched rigid annual herb 9–40(–100) cm. tall, with a ± simple root; stem densely covered with spreading white hairs. Leaf-blades very narrowly elliptic-lanceolate, 2–5.5 cm. long, 1.2–5.5 mm. wide, acute at the apex, narrowed at the base into the stipule-sheath, with scattered long hairs above and on the midnerve beneath or ± entirely glabrous save for the obscurely scabrid margins; midrib and margins distinctly thickened, white; stipules often white, base 4 mm. long, hairy, bearing 5–9 fimbriae 6.5 mm. long. Flowers in very dense terminal heads consisting of several condensed nodes, the leaves of which form radiating bracts, often without any further flowers at lower nodes but if so then these are smaller heads terminating undeveloped lateral branches; bracts of 2 sorts, one leaf-derived, ovate-lanceolate, 5–7 mm. long, 1.5–2 mm. wide, hyaline at the base, stiff and green at the apex, the others stipule-derived of narrow thin fimbriae 3 mm. long from a narrow base. Calyx-tube narrowly oblong, 2 mm. long, hairy above; lobes 4, filiform, 1.5 mm. long, hairy. Corolla greenish or white; tube funnel-shaped, 1 mm. long; lobes ovate-triangular, 0.6 mm. long, 0.4 mm. wide. Filaments exserted 0.5 mm. Style 1.3 mm. long; stigma 0.2 mm. wide. Capsule compressed-cylindrical, 3 mm. long, 1.2 mm. wide, with a median furrow, hairy in upper half. Seeds pale brown, oblong-ellipsoid, 1.8 mm. long. 0.7 mm. wide, 0.4 mm. thick, shiny. Fig. 49/12, p. 340.
