Persicaria sp. 'Porto Velho'

Persicaria sp. 'Porto Velho' is a knotweed originating from Brazil whose species has not yet been reliably determined; it is probably Persicaria rubricaulis.¹ In Europe the plant is rare.¹ Like P. praetermissa, it has narrow leaves whose blade is truncate or hastate at the base and clearly set off from the petiole; 'Porto Velho', however, grows larger and has longer leaves.¹²

Submersed, the shoots grow lying flat to obliquely upwards and reach approx. 30–40 cm in height.¹³ With good lighting and sufficient fertilisation the leaves take on a reddish brown tone, the midrib remains paler and the underside is wine red.¹ Above water it creeps or ascends; its stems are then dark red and its leaves medium to dark green.¹ According to one grower's report it is undemanding and thrives even without added CO₂, but is then less colourful.¹