Scientific name

Hydrothrix Hook. f.

Common names




Could be confused with

Hydrotriche, Lagarosiphon, Mayaca, Rotala

Native distribution

eastern Brazil

Species commonly cultivated

Hydrothrix gardneri Hook. f. (Brazil)

Adventive distribution


Weed status



submerged, delicate, rooted stem plant

Brief description

Annual. Delicate narrow branching stems, with adventitious roots produced at nodes. Leaves in whorls of 7-30, regularly spaced along entire stem, sessile; leaf blade elongate, linear, sheathed at base. Inflorescence axillary, subtended by a green spathe. Flowers paired (superficially appearing as a single flower); perianth tubular, of 6 tepals in 2 whorls of 3, lobes unequal, yellow. Flowers are self-fertilized if they are unopen (cleistogamous) under water, or they open above water and are fertilized by insects. Dispersal is by seed.

Natural habitat

still or slow moving waters such as lakes, ponds, and large rivers

Additional comments

The only species in the genus Hydrothrix, H. gardneri is a delicate plant that is rarely cultivated in aquaria due to its short life span.