Full bloom of ottelia acuminata on Lugu Lake

Ottelia acuminata, an edible aquatic plant endemic to southwest China, is in full bloom on Lugu Lake in Yunnan province. [Photo by Luo Hua/for chinadaily.com.cn]

The plant has been dubbed the "vane" or "touchstone" of water quality.

Water quality and ecological conditions are high-grade when Ottelia acuminata is seen blooming on the water surface.

Lugu Lake is now the most stable lake with the best water quality of the nine plateau lakes in Yunnan, according to the provincial government.