coactio (L.) = a collecting. Rather obscure, what this could refer to.
WCM Protologue Reference:
Mast., Bot. Jahrb. Syst. 29(66): 3 (1900)
Vegetative parts: plants tufted, 0.12–0.5 m tall, basal diameter 1–3 m, crown diameter 10–30 m, compact, without spreading rhizomes or stolons. Fertile culms branching, round (not compressed), solid or with a small central cavity, smooth or finely warty, green, 0.12–0.4 m tall, diameter at base 0.2–0.8 mm, diameter at apex 0.15–0.5 mm. Branch axil indumentum present. Clusters of sterile branches at the nodes of the fertile branches absent. Sheaths more than 1 per culm, persistent, with no abscission line, closely convoluted, 5–12 mm long, margins entire, orange to reddish-brown, with a coppery hue, upper 1/3 in colour and texture similar to the lower 2/3, apical margins coriaceous, like the rest of the body, hyaline shoulders absent, apex, excluding the membranous lobes, acute or obtuse. Sheath-mucro penicellate, straight and erect, 3–7 mm long. Males: male inflorescence with 2–5 spikelets, racemose, 7–15 mm long, 1–3 mm wide. Male inflorescence spathes persistent, shorter than spikelets, cartilaginous. Male spathellae inconspicuous or absent. Male flowers in spikelets. Male spikelets erect on stiff pedicels or sessile, elliptical, apex acute or undifferentiated, 8–12 mm, 1.5–2 mm, with 5–8 flowers, pedicels absent ie spikelets sessile or shorter than the spikelets, flattened. Male bracts taller than flowers, 7–8.5 mm long, elliptical, rounded or obtuse, margins entire, cartilaginous, bract upper margin like body of bract, bract awn less than half as long as the bract body. Male flower 3.5–4.5 mm long. Male tepals sepals and petals the same rigidity, chartaceous, oblong, inner and outer tepals the same length. Male outer lateral tepals conduplicate, keel sparsely villous (bushy white hairs particularly at the tip of the outer tepals). Anthers 2–2.7 mm long, exserted from the flowers. Females: female inflorescence 8–14 mm long, 1–6 mm wide, with 1 spikelet or 2–5 spikelets. Female spathes shorter than the spikelets, persistent, bony or cartilaginous. Female spikelet sessile or pedicel simple, elliptical or obovate, apex acute or undifferentiated, 6–12 mm long, with 4–8 flowers, with 0 sterile bracts. Female bracts taller than flowers, erect, 8–11 mm long, oblong or elliptical, acute, bony or cartilaginous, apical margin like rest of bract, same as body of bract, margins entire, awn less than half as long as the bract body. Female flower 4.5–6 mm long, without a fleshy pedicel, six tepals. Female tepals cartilaginous, keels of lateral sepals sparsely villous (bush of white hair at the tip of outer tepals), midrib flush with the tepal body, margins entire, apices acute, inner and outer whorls the same length. Female outer lateral tepals conduplicate, 4.5–5.5 mm long. Female odd outer tepal ovate, 4.5–5.5 mm long. Female inner tepals ovate, 4.5–5.5 mm long. Staminodes absent. Styles feathery, 2. Style bases fused to form a pillar. Ovary with 2 locules, dehiscent. Fruit: seed 1.4–1.9 mm long, 0.7–1 mm in diameter, shape in side view ovate or oblong, shape in diameter somewhat flattened in cross section, silvery or white, pitted.