Persicaria Sao Paulo

Care at a glance

Overview

One of the most intensely coloured stem plants available, turning deep magenta to wine red under strong light with CO2 and generous macro and iron dosing. Grows fast and strictly upright, so plant single stems in a loose group in the mid to background and top-and-replant to keep it bushy. Weak light or low nutrients leave it a dull olive green with none of the trademark colour.

In the wild

An undescribed knotweed collected near Sao Paulo, Brazil, thought to belong to the widespread wetland species Persicaria hydropiperoides. In the wild these smartweeds grow along the muddy margins of ponds, ditches and slow streams, rooting in the shallows and pushing emersed shoots above the surface. Like most Persicaria it lives an amphibious life, switching between a green terrestrial form and a red submersed one.

Good to know

Belongs to Polygonaceae, the knotweed and smartweed family, recognisable by the papery sheath (ochrea) wrapping each node. It has never been formally described to species, so it circulates in the hobby only under its collection name. It was long sold as Polygonum before that genus was split and the aquatic smartweeds moved to Persicaria.

Did you know

Its red submersed colour is a sunscreen response: the plant floods its leaves with anthocyanin pigments under bright light, which is why the same stem grows plain green emersed and vivid magenta once it is underwater.

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