The Small-headed knotweed (Persicaria microcephala) belongs to Polygonaceae (the Knotweed family). It is a perennial herb that is distributed around the Himalayas and in central and southern China. It grows in mixed forests on mountain slopes and in grasslands of valleys, and grows to a height of about 50 cm. The leaves are ovate to long ovate with reddish-purple veins. Small, pale pink flowers bloom in spikes at the top of the stem from July to August. This plant has been introduced to the Unite Kingdom, and one of its varieties, the "Red Dragon", was awarded the Garden Merit Medal by the Royal Horticultural Society of Great Britain. In Chinese, it is called "小頭蓼" (xiao tou liao).