regnum-plantae:

Persicaria affinis ‘Superba’, Polygonaceae

After a very gloomy January day I find myself looking at photos of sunny, late-summer afternoon at Glasgow Botanic Gardens, so here’s a showy cultivar of what is commonly known as knotweed, or bistort, the third Persicaria which features on my blog after the common slender knotweed (P. decipiens) and the just as colourful red bistort (P. amplexicaulis). P. affinis shares part of its range in the Himalayas with the latter, but is also native to Pakistan, where it is found on rocky slopes, riverbanks and pastures, generally in presence of moisture and in partial shade. 

It has been introduced in temperate areas for its ornamental value as a fully hardy, perennial, semi-evergreen groundcover which forms dense mats and puts on a beautiful floral show through late summer and autumn, with spikes that gradually change colour as the blooms open. As the first frosty nights arrive, when the persistent flower spikes are already spent, the leaves turn a bright red before disappearing for the winter rest. In its native area the flowers have also been used medicinally to treat fevers, but if you plant it in your garden you can leave them to the bees and the rest of wildlife, which will benefit from this source of pollen and nectar in the season when everything starts going dormant.