Bistorta perpusilla (Hook.f.) Greene, Leafl. Bot. Observ. Crit. 1: 21 1905. (Syn: Polygonum perpusillum Hook. f.);
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East Himalaya, Nepal, West Himalaya as per POWO;
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Common name: Tiny Knotweed
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Polygonaceae Fortnight polygonum perpusillum from Rohtang Pass ,Kullu Dist, HP : 3 posts by 3 authors. Attachments (1).
Shot from Rohtang zero Point at 4000m

A very good finding …! Big thanks for sharing this typical alpine Himalayan element!!
Better to call it Bistorta perpusilla (Hook. f.) Greene 


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Bistorta perpusilla (Hook.f.) Greene (Polygonaceae) photographed above Bhagwabasa, Roopkund area (Chamoli) Uttarakhand. Second image is a cropped up part of first.
2600m altitude.