Persicaria hydropiper

Care at a glance

Overview

A fast stem for the midground that trades between two looks: vivid green and magenta emersed growth in a paludarium, and softer, narrower leaves in green to pink tones once submersed. Plant bare stems a few centimeters apart in rich substrate; the emersed leaves will drop as underwater ones replace them, which looks alarming but is normal. Colour depends on what you give it: medium light keeps it green, while strong light, CO2 and iron-rich dosing pull out the pink and red. It grows quickly when settled, so top and replant to keep the group dense. The natural home for this species is the wet margin of a riparium or bog planter, where it is close to foolproof.

In the wild

A widespread annual of damp ground across temperate Europe, Asia, North America and Australia, growing on muddy banks, in ditches and at the shallow edges of ponds and streams. It is an amphibious marginal rather than a true aquatic: wild plants stand emersed with their feet wet, and only the lower stems spend time underwater. Nursery stock is grown emersed and converts to an underwater form in the tank.

Good to know

A knotweed in the family Polygonaceae, long known as Polygonum hydropiper before the genus was split. The species name means water pepper, earned by the sharp peppery bite of the leaves, which comes from the compound polygodial. It has the family's typical jointed stems with sheathing stipules at each node and slender, lance-shaped leaves.

Did you know

In Japan this is tade, a culinary herb: the peppery red seedlings, benitade, are the tiny sprout garnish served beside sashimi, and the same bite is why grazing animals leave the wild plant alone.

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