HARBIN - The number of an endangered water plant is on the rise in a nature reserve in Northeast China's Heilongjiang province, authorities said.

More than 20,000 waterwheel plants, a wild plant under Class-I national protection in China, have been found in the Qixinghe National Nature Reserve, according to the reserve's management bureau.

The waterwheel plants, which have been found to grow in Europe, Asia and Africa, have very high requirements for their environment. In September last year, about 5,000 such plants were discovered in the reserve for the first time.

Authorities have since stepped up efforts to protect the plants. According to the bureau, the plants in the wetland in Qixinghe have strong reproductivity. They can help purify the water, which can help improve the environment.