Species commonly cultivated
Tonina fluviatilis Aubl. (South America)
information not available
Perennial. Stems slender, branched. Leaves cauline, alternate or spiral, sessile, narrow, elongate, lanceolate to short-ovate, veins parallel, without cross-veins; margin entire. Flowers in spiny heads borne on short peduncles from leaf axils. Flowers small, unisexual; perianth segments in 2 somewhat differentiated whorls of 3; female perianth segments fringed with hairs; inner segments minute. Dispersal presumably by seeds or stem fragments.
mostly in relatively slow flowing or still waters
A single species is in this genus, Tonina fluviatilis. Numerous varieties of this plant (varying in leaf dimensions) are traded, usually under the name of the river system from which they were originally collected.