Back from the brink

After gradually disappearing in the 1980s, flea grass has undergone a remarkable revival.

In the 1980s, ethnobotanist Pei Shengji was the first to systematically document the characteristics and traditional uses of flea grass among the Hani people in the villages surrounding the Xishuangbanna Tropical Botanical Garden of the Chinese Academy of Sciences.

When Hu Huabin, a senior researcher at the botanical garden and a student of Professor Pei, started working in Xishuangbanna in 1983, he often noticed Hani people coming down from the mountains to the local market wearing leaves or flea grass floral ornaments.

However, as destructive land-use practices such as slash-and-burn agriculture were gradually being phased out, upland rice fields disappeared, along with the flea grass that grew wild alongside them, according to Hu.

The Hani people relocated from the mountains to settle in areas with better infrastructure, which provided them with better living and healthcare conditions. As a result, flea grass was slowly forgotten.

It wasn't until the 2010s, when Hu's team began surveying plants in southern Yunnan for possible commercial use, that flea grass reentered the public spotlight.

Hu said the main challenge in cultivating this wild plant was its tiny seeds being too small to effectively compete with weeds and crops for nutrients. Other hurdles included identifying the optimal planting time, and enhancing the extraction rate of its essential oil.

Hu's team first nurtured and rejuvenated flea grass seedlings then transplanted them in their natural environment. Weeding and irrigation programs were also commenced.

After repeated experiments, the team discovered that the ideal time to plant flea grass is in late May. By carefully controlling the temperature during processing, they were able to achieve an essential oil extraction rate of up to 0.38 percent.