Persicaria microcephala

Persicaria microcephala (syn. Polygonum microcephalum), the small-headed knotweed, is a species of flowering plant in the family Polygonaceae. It is native to the Himalayas, and central and southern China, and it has been introduced to Great Britain. Its cultivar 'Red Dragon' has gained the Royal Horticultural Society's Award of Garden Merit.

Subtaxa
The following varieties are accepted:
 * Persicaria microcephala var. microcephala
 * Persicaria microcephala var. sphaerocephala (Wall. ex Meisn.) H.Hara