Australian Tropical Rainforest Plants - Online edition

Persicaria hydropiper (L.) Delarbre

Herb (herbaceous or woody, under 1 m tall)
Shrub (woody or herbaceous, 1-6 m tall)
Click/tap on images to enlarge
Flowers. © CSIRO
Scale bar 10mm. © CSIRO
Cotyledon stage, epigeal germination. © CSIRO
10th leaf stage. © CSIRO

Delarbre, A. (1800) Flore de la ci-devant Auvergne. Flore d' Auvergne Edn. 2, 2: 518

Common name

Water Pepper; Pepper, Water


Usually flowers and fruits as a weedy shrub about 1-2 m tall.


Leaf blades about 12.5-13 x 1.5-2 cm, petioles about 1-1.5 cm long, slightly winged. Stipules about 1.8-2.1 cm long, fused to form a fringed sheath enclosing the stem. Lateral veins about 18-20 or more on each side of the leaf blade.


Perianth segments about 2-3 mm long, with numerous small glands on the outer surface. Stamens 7 alternating with 7 small glands at the base.


Style and stigma persistent at the apex and the rest of the fruit enclosed in the persistent perianth. Each nut about 2-2.5 x 1.5-2 mm, seeds solitary, slightly smaller. Embryo white, about 1.5-2 mm long. Cotyledons shorter but wider than the radicle.


Cotyledons about 7-8 x 4 mm, petioles about 2-3 mm long. First pair of leaves elliptic to ovate, about 17 x 6 mm, apex acute to apiculate, base cuneate to attenuate. At the tenth leaf stage: petiole with sheathing membranous base which surrounds the stem for about 5-20 mm. Seed germination time 27 days.

Distribution and Ecology

Occurs in WA, NEQ, CEQ and southwards to Victoria and westwards to Western Australia. Altitudinal range in NEQ not known but collected at 600 m. In NEQ grows in disturbed rain forest in close proximity to water. Widespread in the northern hemisphere.

Polygonum hydropiper L., Species Plantarum 2: 361(1753), Type: Habitat in Europae subhumidis.  Persicaria hydropiper (L.) Spach, Histoire Naturelle des Vegetaux 10: 536 (1841).
RFK Code
Copyright © CSIRO 2020, all rights reserved.