Elatine triandra

Long Stem Waterwort

Long Stem Waterwort, Elatine triandra
Long Stem Waterwort

Flora, fauna, earth, and sky...
The natural history of the northwoods


  • Elatine, from the Greek, 'elatinos (elatinos), "of the fir"; used by Pliny to refer to a plant of the genus Antirrhinum (Snapdragons).
  • triandra, from the Latin, tri, "three", and the Greek 'andros (andros), "male"; hence, "three stamens"
  • Common name from its size relative to the more common, in our area anyway, Small Waterwort (Elatine minima)
  • Other common names include: Three Stamen Waterwort, Úpor Trojmuzný (Cz), Trehannet Bćkarve (Dan), Kolmihedevesirikko, Kolmiheteinen vesirikko (Fin), Dreimänniger Tännel (Ger), Trefelt evjeblom (Nor), Troprašna jelovka, Trolistni Vodni Poper (Si???), Elatinka Trojtyčinková (Slovak), Tretalig Slamkrypa (Swe)


  • Kingdom Plantae, the Plants
    • Division Magnoliophyta, the Angiosperms (flowering plants)
      • Class Magnoliopsida, the Dicotyledons
      • Subclass Dilleniidae
        • Order Theales,
          • Family Elatinaceae, the Waterworts
            • Genus Elatine, the Waterworts
  • Taxonomic Serial Number: 21413
  • Also known as Elatine americana, Elatine brachysperma


  • A small, matted, annual herb
  • Leaves opposite, sessile, obovate to oblanceolate, 3mm-12 mm long, 1mm-3 mm wide, mostly truncate or emarginate at the tip, entire. Minute membranous stipules in leave axils.
  • Stem rather fleshy, smooth, densely branched from the base, the branches sprawling or floating, often rooting at the nodes, 1"-6" long.
  • Roots unbranched, thread-like
  • Flowers small, perfect, sessile, and solitary in the leaf axils, 1.5mm-2 mm across
    • Sepals 3
    • Petals 3
    • Stamens
    • Pistil 3 styles
    • Ovary superior (within blossom), 3 chambers
  • Fruit a globose capsule, 1-1.5 mm in diameter, membranous;
  • Seeds many, golden-yellow, oblong, about 0.5 mm long, ridged and obscurely pitted in rows


  • A small, inconspicuous plant of muddy shores and very shallow waters.
  • Distinguished from other small, inconspicuous shoreline plants by its opposite leaves with small, membranous stipules in the leaf axils.
  • Distinguished from the closely related, and in our area much more common, Small Waterwort (Elatine minima) by having flowers with 3 sepals and 3 petals rather than 2.


  • Wisconsin to Alberta and Washington, south to Texas, northern Mexico, and California. Also Eurasia.
  • Species of Special Concern in Wisconsin


  • Mud flats or floating in the shallow waters of lakes and ponds; rare and scattered.





  • By seed
  • Flowers July-September


  • By seed


  • Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
  • Not known to be available commercially.



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Last updated on 26 February, 2004