Description from Flora of China
Herbs aquatic, perennial, glabrous, with creeping rhizomes. Stems submerged or emergent, erect, simple, leafy. Leaves estipulate, whorled, sessile, simple, linear to ovate, margin entire. Flowers solitary in axils of upper leaves, sessile, minute, bisexual or unisexual, Perianth reduced to an entire rim on top of ovary. Stamen 1, epigynous. Ovary inferior, 1-loculed; ovule 1, pendulous, anatropous, micropyle closed; style filiform, with stigmatic papillae down one side. Fruit a small achene.
Hippuris and Callitriche Linnaeus (to be treated in Callitrichaceae in Fl. China 11) are sister genera and, together with several genera already treated in the Scrophulariaceae (see Fl. China 18. 1998), are now regarded as belonging with Plantago Linnaeus in an expanded Plantaginaceae; see Olmstead et al. (Amer. J. Bot. 88: 348-361. 2001), who incorrectly used the name Veronicaceae for this group instead of Plantaginaceae.
Wan Wenhao. 2000. Hippuridaceae. In: Chen Chiajui, ed., Fl. Reipubl. Popularis Sin. 53(2): 144-147.
One genus and two species: temperate regions worldwide, mainly in the N hemisphere; two species in China.
(Authors: Chen Jiarui (陈家瑞 Chen Chia-jui); A. Michele Funston)