Bistorta affinis (synonyms Polygonum affine, Persicaria affinis), the Himalayan bistort,[2] fleece flower, or knotweed, is a species of flowering plant in the family Polygonaceae, native to the Himalayas (Tibet, Nepal, northern India, Pakistan, Kashmir).

The narrow elliptic leaves are white on the underside because of a waxy coating.

Cylindrical spikes of many pale pink or rose-red flowers are borne at the top of short erect stems, from midsummer to autumn.

[3][4] Bistorta affinis is found in the Himalayas, from Afghanistan to eastern Nepal, at altitudes of 3,000–4,800 m (9,843–15,748 ft).

[6] Under the synonym Persicaria affinis the following cultivars have gained the Royal Horticultural Society's Award of Garden Merit:[7] Media related to Bistorta affinis at Wikimedia Commons