Persicaria hydropiperoides

Persicaria hydropiperoides (= Polygonum hydropiperoides) is a knotweed native to large parts of North, Central and South America. The species name refers to its likeness to water pepper (Persicaria hydropiper), which is also found in Europe. P. hydropiperoides is almost always found on (stagnant) waterbodies, and it often grows partially sumbersed, other than most North-American knotweed species, also other than those that can grow submersed. Its rather straight upright inflorescence and the tiny white flowers make it easy to identify. However, P. hydropiperoides is a very variable species. In its North-American habitat it is easily obtained by colleting it in the wild, or from other hobbyists. In Europe, however, this knotweed is still pretty much unknown as aquarium plant and probably not avaiable in trade either.

Even though its green colour is not as striking as the hues of related species, this plant has its very own subtle beauty. Even though P. hydropiperoides may survive and even grow under low lights it develops far better under strong lights and with an ample nutrient supply. Then the leaves develop a highly undulate form and look their liveliest. Differently from other North-American knotweed species, the internodes of P. hydropiperoides are not very long. This plant maintains its strict upright growth habit under all conditions. This knotweed does not grow very high, but it is not really small either, and needs room. An aquarium of 150 litres or more is recommendable.

This knotweed is a good back- or middleground plant. When used in the middleground, its optical effect is most favourable if it is planted as a solid, dense group. P. hydropiperoides makes a phantastic backdrop for red plants, and it can also be used as interesting structural element in a lush, purely green aquascape. An especially fine combination can be created together with the related knotweed P. sp. ’Sao Paulo’. The latter is similar in structure and growth habit, but has a totally different colour - magenta red.