Description from Flora of China
Sagittaria altigena Handel-Mazzetti ex Samuelsson; S. sagittifolia Linnaeus var. pygmaea (Miquel) Makino.
Plants stoloniferous. Petiole indistinct; leaf blade linear or subspatulate, 2-29 cm × 2-11 mm, sheathing basally, apex acuminate or obtuse. Inflorescences racemose, 1-10 cm, in 2 or 3 whorls of 3 flowers; bracts elliptic. Flowers unisexual; female flowers not exceeding 2, restricted to lowest whorl, sessile or only with very short pedicels; male flowers with pedicels 0.5-3 cm. Sepals obovate, 5-7 × 3-5 mm. Petals orbicular, 1-1.5 × 1-1.6 cm. Stamens 6-21; anthers yellow. Achenes broadly obovoid, 3-5 × 3-3.5 mm, abaxially cristate, with a broad wing and an adaxial beak. Fl. and fr. May-Nov. 2n = 22*.
Specimens with one whorl of staminodes and leaves retuse at apex from Dongchuan, Yunnan, which were described as Sagittaria altigena, appear to be in the range of variety of this species rather than a distinct taxon.
Paddy fields, marshes, and channels. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Taiwan, Yunnan, Zhejiang [Japan (including Ryukyu Islands), Korea, Thailand, Vietnam].