vallis (L.) = valley, + simius (L.) = baboons. After "Baviaanskloof", the type locality.
WCM Protologue Reference:
H.P.Linder, Bothalia 15: 462 (1985)
Vegetative parts: plants single isolated shoots, 0.5–1 m tall, compact, without spreading rhizomes or stolons. Fertile culms branching, smooth, olivaceous, 0.5–1 m tall, diameter at base 2.5–5 mm, diameter at apex 0.3–0.7 mm. Sheaths closely convoluted, 8–20 mm long, pale-brown, turning grey with age, apical margins narrowly membranous, hyaline shoulders absent or membranous margins continuing behind awn, hyaline shoulder 0.05 of sheath body length, apex, excluding the membranous lobes, acuminate or acute. Sheath-mucro penicellate, straight and erect, 2–4 mm long, apically decaying, changing appearance. Males: male inflorescence with 2–5 spikelets or 6–10 spikelets or 11–20 spikelets. Spathes like sheaths. Male flowers in spikelets. Male spikelets erect on stiff pedicels or sessile, 10–15 mm. Male bracts taller than flowers or more than twice as tall as flowers, 5–10 mm long, acute, chartaceous or cartilaginous, bract upper margin like body of bract, bract awn minute or absent. Male flower 3–4 mm long. Male tepals sepals more rigid than petals, cartilaginous, petals membranous. Male outer lateral tepals conduplicate, glabrous or keel sparsely villous. Anthers exserted from the flowers. Pistillode present. Females: female inflorescence paniculate or racemose, 25–40 mm long, 10–15 mm wide, with 2–5 spikelets or 6–10 spikelets. Female spathes shorter than the spikelets, persistent, coriaceous. Female spikelet sessile, oblong, apex truncate or rounded, 10–20 mm long, with 5–10 flowers, with 1 sterile bracts. Female bracts at least twice as long as flowers, 8–12 mm long, oblong, acute, cartilaginous, apical margin like rest of bract, same as body of bract, awn minute or absent. Female flower 4–6 mm long, without a fleshy pedicel. Female tepals cartilaginous, keels of lateral sepals sparsely villous, midrib flush with the tepal body, apices acute, inner and outer whorls the same length. Female outer lateral tepals conduplicate, 4–6 mm long. Female odd outer tepal linear or oblong, 4–6 mm long. Female inner tepals linear or ovate, 4–6 mm long. Staminodes present. Styles feathery, white, 3. Style bases free. Ovary with 2 locules, dehiscent. Fruit: seed 2 mm long, shape in diameter triangular in cross section, smooth (shiny).