A century ago, British botanist George Forrest found a huge rhododendron in southwest China. He sent a trunk sample back to Britain that shocked the local field of botany.
The tree he discovered in Yunnan province in 1918 measured 25 meters high and 87 cm in diameter at breast height. It was previously believed that all rhododendrons were low shrubs.
Rhododendron protistum var. giganteum, or big tree rhododendron, stands out for its large trunk and spectacular flowers. In China, plants usually fall within the height of 2,100 to 3,200 meters above sea level in the Gaoligong Mountains, which are home to about 17 percent of tall plants, about 30 percent of mammals and 35 percent of the birds in the country.
The species is regarded as the "King of Rhododendron Species" among some 960 species globally. It was categorized as critically endangered by the International Union for Conservation of Nature for its small population and restricted distribution.
Sun Weibang, director of the Kunming Botanical Garden, under the Kunming Institute of Botany of the Chinese Academy of Sciences, said that Chinese rhododendrons brought more colors to western gardens.
As Forrest and other botanists introduced hundreds of rhododendron species from China to Britain, the country was on the fast track to be a rhododendron cultivation center in the world.
For more than six decades after 1918, the field of botany conducted few investigations or specimen collections of big tree rhododendrons and had scarce research results. Forrest's record once became the sole source for research on the species.
It was not until 1981 that Feng Guomei, a botanist with the Kunming Institute of Botany, found the big tree rhododendron again in the deep mountains of Datang Village. They discovered more than 40 well-grown rhododendrons.
The next year, local authorities sent an investigation team to the hinterland of the Gaoligong Mountains and found a new community of the species. Among them, 12 were about 100 cm in diameter at breast height, and the largest one had a basal diameter of 307 cm, which has grown to 330 cm to date and is considered the largest one across the globe.
Through decades of efforts, remarkable results have been achieved in the preservation and artificial breeding of this species, which has become a model for saving plants with extremely small populations in China.
According to Huang Xiangyuan, a senior official with the Gaoligong Mountains Nature Reserve, the Datang branch of the reserve hosts 1,771 big tree rhododendrons, of which over 500 are seedlings or saplings, and some 1,200 are adult trees.
Li Guixiang, a researcher with the Yunnan Academy of Forestry and Grassland, said that his team has produced more than 30,000 seedlings, providing technical guarantees for artificial breeding and population recovery of the species.
In May 2021, 300 high-quality seedlings provided by the academy were planted at a botanical garden and a monitoring station in the Gaoligong Mountains.
"Now, the seedlings are growing well. But the species grows very slowly and our team is waiting for them to mature," said Li.
The Kunming Institute of Botany is also keeping seeds of big tree rhododendrons in cold storage at minus 20 degrees Celsius for better protection of the species.
In 2010, the Yunnan provincial government approved an outline of a 10-year plan for the rescue and protection of such species in the province, listing out 62 plants and 50 animals, including the big tree rhododendron. It was followed by a five-year national program beginning in 2011 to rescue plant species with extremely small populations.
In 2021, Yunnan authorities upgraded its protection list of wild plants with extremely small populations, and the big tree rhododendron was removed from the list.
