rigidus (L.) = rigid. In reference to the leaf-blades on the sterile shoots, which are rigid, compared to those of the closely related T. cinereus, which are long and soft.
WCM Protologue Reference:
Esterh., Bothalia 15: 477 (1985)
Vegetative parts: plants tufted, 0.5–1 m tall, basal diameter 0.05–0.15 m, crown diameter 0.1–0.5 m, compact, without spreading rhizomes or stolons. Fertile culms unbranched, velvety pubescent, silvery-gray, 0.5–1 m tall, diameter at base 1.5–2.5 mm, diameter at apex 1–2 mm. Clusters of sterile branches at the nodes of the fertile branches present. Sterile branches present post flowering. Sheaths closely convoluted, 30–60 mm long, red brown to pale tan, apical margins broadly chartaceous and soon decaying, hyaline shoulders absent, apex, excluding the membranous lobes, acute. Sheath-mucro absent. Sterile branch leaf-sheath 1.5–3 mm long, hyaline shoulder 1–2 mm long, lacerated, leaf-blade 3–4 mm long; leaf blade 0.3–0.5 mm wide. Males: male inflorescence with 11–20 spikelets or 21–50 spikelets or 50–100 spikelets, paniculate, 100–250 mm long, 20–100 mm wide. Male inflorescence spathes persistent, upper margins lacerated and largely decayed at anthesis, shorter than spikelets, chartaceous. Male flowers in spikelets. Male spikelets pendulous on flexible pedicels, oblong, apex rounded, 10–35 mm, 5–10 mm, with 18–36 flowers, pedicels shorter than the spikelets, flattened. Male bracts taller than flowers, 7–9 mm long, oblong, acute, chartaceous or cartilaginous, bract upper margin like body of bract, bract awn minute or absent, pale brown to cream-coloured. Male flower 3.3–4.3 mm long. Male tepals sepals and petals the same rigidity, chartaceous or cartilaginous, square, inner and outer tepals the same length. Male outer lateral tepals conduplicate or keeled or winged, glabrous. Anthers 1.5–2 mm long, included in the flowers. Pistillode absent. Females: female inflorescence linear or paniculate or racemose, 70–200 mm long, 15–40 mm wide, with 11–20 spikelets. Female spathes longer than the spikelets, not obscuring spikelet, persistent, chartaceous. Female spikelet pedicel simple or pedicel sparsely branching, oblong, apex rounded, 10–25 mm long, with 3–25 flowers, with 0 sterile bracts. Female bracts taller than flowers, oblong, acute, hyaline or cartilaginous, apical margin like rest of bract, same as body of bract, awn minute or absent. Female flower 4.5–5 mm long, without a fleshy pedicel. Female tepals chartaceous or cartilaginous, glabrous and smooth, at least as tall as nut, wrapped around it and obscuring the surface, midrib flush with the tepal body, apices acute, inner whorl shorter than outer. Female outer lateral tepals keeled or winged, wings entire, wings lateral sepals decurrent, without grooves, wider than body, exserted past bracts and overlapping with one another, 4.5–5 mm long. Female odd outer tepal oblong, 3–4 mm long. Female inner tepals oblong, 3–4 mm long. Staminodes absent. Styles plumose, white, 1. Ovary with 1 locule, indehiscent. Fruit: indehiscent fruits with a softer ovary wall. Perianth presence on fruits persistent, winged. Shape of winged dispersal unit orbicular. Nut apex smooth, without a distinct cap, wall smooth (rough in apical half with tuberculate epidermal cells), (1.84–)2.07(–2.24) mm long, (1.16–)1.34(–1.76) mm diam., shape in side view elliptical, shape in top view elliptical in cross section (with lateral ridges), brown (very dark). Elaiosome absent.