humilis (L.) = low, low-growing. This is indeed one of the shortest species of Willdenowia.
WCM Protologue Reference:
Nees ex Mast., J. Linn. Soc., Bot. 10: 272 (1869)
Vegetative parts: plants tufted, 0.3–1 m tall, basal diameter 0.2–0.4 m, crown diameter 0.4–0.8 m, compact, without spreading rhizomes or stolons or with rhizomes. Rhizome very short with culms aggregated at base or spreading, unbranched or sparsely branched, culms evenly spaced, 4–6 mm in diam., culms 1–4 mm apart. Fertile culms unbranched, finely warty or finely rugulose, olivaceous or speckled golden, 0.5–1 m tall, diameter at base 0.5–2 mm, diameter at apex 0.3–1 mm. Sheaths closely convoluted or loosely convoluted, 10–35 mm long, brown, (same as culm), variously with yellow borders (coriacious portion of sheath), apical margins broadly membranous, hyaline shoulders absent, apex, excluding the membranous lobes, acuminate or acute or obtuse. Sheath-mucro penicellate or awl- or needleshaped, straight and erect or twisted, 2–10 mm long, older sheaths truncate due to membranous apex decaying. Males: male inflorescence with indefinite spikelets, Paniculate, 30–100 mm long, 6–12 mm wide. Male inflorescence spathes caducous, taller than spikelets, chartaceous or cartilaginous, sheath-like but expanded. Male flowers not aggregated into spikelets. Male bracts taller than flowers, 5–10 mm long, linear, acute, lax, chartaceous or membranous, bract upper margin like body of bract, bract awn minute or absent, caducous, standing out from spikelet. Male flower 3–4 mm long. Male tepals sepals and petals the same rigidity, chartaceous or membranous, linear (hair-like), inner and outer tepals the same length. Male outer lateral tepals as other tepals, glabrous. Anthers 2–3 mm long, included in the flowers. Pistillode absent. Females: female inflorescence linear or racemose, 20–100 mm long, 1.6–2.2 mm wide, with 1 spikelet or 2–5 spikelets. Female spathes longer than the spikelets, obscuring spikelet, persistent, coriaceous or cartilaginous. Female spikelet sessile, linear or elliptical, apex acute, 10–20 mm long, with 1 flowers, with 4–8 sterile bracts. Female bracts taller than flowers, 5–10 mm long, linear or oblong, acute or acuminate, chartaceous or membranous, apical margin like rest of bract, same as body of bract, awn minute or absent. Female flower 6–8 mm long, without a fleshy pedicel. Female tepals chartaceous or membranous, glabrous and smooth, smaller than nut and not obscuring the nut surface, midrib flush with the tepal body, apices acuminate, inner and outer whorls the same length. Female outer lateral tepals like other tepals, 5–6 mm long. Female odd outer tepal linear or oblong, 5–6 mm long. Female inner tepals linear or oblong, 5–6 mm long. Staminodes absent. Styles plumose, white, 2. Style bases free. Ovary with 1 locule, indehiscent. Fruit: indehiscent fruits with a hard woody ovary wall. Perianth presence on fruits persistent, membranous, shorter than nut. Nut cap with several rows of ridges, wall tuberculate, 6–8 mm long, 1.8 mm diam., shape in side view oblong, shape in top view round in cross section, green. Elaiosome absent.