rarus (L.) = rare, infrequent: presumably referring to its rarity.
WCM Protologue Reference:
Esterh., Bothalia 15: 459 (1985)
Vegetative parts: plants tufted, 0.2–0.4 m tall, basal diameter 0.01–0.05 m, crown diameter 0.05–0.2 m, compact, without spreading rhizomes or stolons. Fertile culms branching, finely rugulose or finely warty, olivaceous, 0.2–0.4 m tall, diameter at base 0.2–0.5 mm, diameter at apex 0.05–0.1 mm. Sheaths closely convoluted, 7–16 mm long, pale brown, apical margins narrowly membranous, hyaline shoulders tall, acute, hyaline shoulder 0.3–0.6 of sheath body length, apex, excluding the membranous lobes, acute or rounded. Sheath-mucro penicellate, straight and erect, 2–4 mm long. Males: male inflorescence with 1 spikelet. Male inflorescence spathes persistent, like the floral bracts, chartaceous. Male flowers in spikelets. Male spikelets erect on stiff pedicels or sessile, oblong or obtriangular, apex truncate, 8–15 mm, 4–8 mm, with 5–6 flowers, pedicels absent ie spikelets sessile. Male bracts more than twice as tall as flowers, 6–10 mm long, oblong, acute or acuminate, chartaceous, bract upper margin like body of bract, bract awn less than half as long as the bract body, pale brown, concolorous. Male flower 3–3.3 mm long. Male tepals sepals more rigid than petals, cartilaginous, petals chartaceous, oblong, inner and outer tepals the same length. Male outer lateral tepals conduplicate, keel sparsely villous. Anthers 1.5–1.7 mm long, exserted from the flowers. Pistillode present (minute). Females: female inflorescence with 1 spikelet. Female spathes shorter than the spikelets, persistent, chartaceous or cartilaginous. Female spikelet sessile, obtriangular, apex truncate, 7–14 mm long, with 2–5 flowers, with 1 sterile bracts. Female bracts at least twice as long as flowers, 6–10 mm long, oblong, acuminate, chartaceous, apical margin like rest of bract (the whole bracts with scattered foveolate cells), same as body of bract, awn minute or absent. Female flower 2.7–4 mm long, without a fleshy pedicel. Female tepals cartilaginous, keels of lateral sepals sparsely villous, midrib flush with the tepal body, apices acute, inner whorl shorter than outer. Female outer lateral tepals conduplicate, 2.8–4 mm long. Female odd outer tepal oblong, 2.8–3.5 mm long. Female inner tepals oblong, 2.5–3.5 mm long. Staminodes present. Styles feathery, 3. Style bases free. Ovary with 2 locules, dehiscent. Fruit: seed 1–1.25 mm long, 0.5–0.6 mm in diameter, shape in side view elliptical, shape in diameter round in cross section or plano-convex in cross section, grey, smooth.