Ann. Sci. Nat. 451, t. 12 (1829)
Annual or perennial herbs. Rhizomes much-branched bearing roots, scale leaves and erect leafy shoots at nodes. Leaves frequently crowded at distal end of branches; floral leaves apparently subopposite; sheath with auricles well-developed; lamina linear. Flowers pedicellate, initially enclosed in a leaf-sheath. Male flowers with pedicel very short initially, elongating considerably at anthesis and extending beyond the leaves; anther or anther mass sessile, and subtended by 3 minute scales or scales fused and cup-like. Female flowers with 3 membranous and persistent scales; ovule 1 per carpel; styles slender. Fruit with style persistent.
9 species, 7 in Australia, 6 occurring in Victoria.
Recent molecular research (Ito et al. 2016) indicated that Lepilaena, as the group was formerly recognised in Australia, is more appropriately included in Althenia, hitherto mostly regarded as a Northern Hemisphere genus. A taxonomic review of the genus in Australia is underway, likely to result in the recognition of further species.
Ito, Y.; Tanaka, N.; Carcia Murillo, P.; Muthana Muasya, A. (2016). A new delimitation of the Afro-Eurasian plant genus Althenia to include its Australasian relative Lepilaena (Potamogetonaceae) - Evidence from DNA and morphological data., Molecular Phylogenetics and Evolution 98: 261–270.