Rheum nobile

Rheum nobile, the Sikkim rhubarb or noble rhubarb (पदमचाल), is a giant herbaceous plant of the Buckwheat Family (Polygonaceae) and native to the Himalayas, from northeastern Afghanistan, east through northern Pakistan and India (in Sikkim), Nepal, Bhutan, and Tibet to Myanmar, occurring in the alpine zone at 4000–4800 m altitude. It is an extraordinary species of rhubarb (genus Rheum). At 1–2 m tall, the monocarpic inflorescences of R. nobile tower above the other shrubs and low herbs in its habitat, and it is visible across valleys from several kilometres. R. nobile is often called a glasshouse plant because of its outer curtain of translucent bracts which pass visible light, creating a greenhouse effect, while blocking ultraviolet radiation. These are likely defenses against the increased UV-B exposure and extreme cold in its high altitude range. It also provides a safe haven for its pollinators against wind and night chill.