eusteralis, Australian hygrophila
tropical regions of Asia and Australia
Species commonly cultivated
Pogostemon helferi (Hook. f.) Press (Thailand)
P. stellatus (Lour.) Kuntze (Asia to Australia)
P. yatabeanus (Makino) Murata (Japan)
Annual or perennial. Stem erect, ascending, with creeping stolon, adventive roots produced from basal nodes. Leaves in whorls of 4 to 10, evenly spaced along stem, but densely packed at apex when submersed, sessile; leaf blade linear to lanceolate, midvein prominent; margin entire to finely serrate. Inflorescence an apical (sometimes axillary) spike of densely arranged, small flowers. Flowers zygomorphic, bisexual; sepals 5; corolla of 4 subequal lobes, pink to purple; stamens 4. Dispersal by seed or stem fragments.
Swamps, rivers, lakes, and floodplains.
Pogostemon consists of approximately 75 species and is distributed throughout tropical Asia and Australia. Dysophylla and Eusteralis are considered synonyms of Pogostemon. Only two species are presently cultivated for aquariums and ponds. In the submersed form, P. stellatus has numerous geographical varieties, but has narrower leaves than P. yatabeanus, and often has red foliage.