Description from Flora of China
Rohrbachia minima (Funck ex Hoppe) Mavrodiev.
Stems 16-65 cm tall, slender. Leaves usually basal, sheathlike, often without blade or sometimes with blade, 15-40 cm × 1-2 mm, shorter than scape. Male part of spikes 3-8 cm, without hair on axis, with 1 deciduous bract at base; female part of spikes distinctly separated from male part, 1.6-4.5 cm, with bract at base. Male flowers: stamens 1, rarely 2 or 3; anthers ca. 1.5 mm. Female flowers with bracteoles; ovary fusiform; stalk ca. 4 mm, slender; styles ca. 0.5 mm; stigmas linear, ca. 0.5 mm; hairs on stalk swelling at tip, shorter than styles. Fruit elliptic. Fl. and fr. May-Aug.
Shallow water of ponds and rivers. Gansu, Hebei, Heilongjiang, Henan, Hubei, Jilin, Liaoning, Nei Mongol, Shaanxi, Shandong, Shanxi, Sichuan, Xinjiang [Afghanistan, Kazakhstan, Kyrgyzstan, Mongolia, Pakistan, Russia, Tajikistan, Turkmenistan, Uzbekistan; SW Asia, Europe].