Is the North American "paratrooper" Erigeron candidum an invasive weed or a treasure trove of traditional Chinese medicine?

In recent years, biological invasion has become one of the hot issues of global concern. Alien invasive weeds are a type of biological disaster that seriously threatens crop production. Erigeron australis, native to North America, has successfully invaded many countries and regions including my country. The fruits of Erigeron australis can be quickly blown away by the wind like "paratroopers" and covered on other plants. Due to its strong ecological destructive power, it often causes huge ecological and economic losses to the local area, so its effective prevention and control is urgent. However, the plant also has anti-inflammatory, hemostatic, diuretic and other effects, and can be used as a Chinese medicinal material. So, is it an invasive weed or a treasure of Chinese medicine?

Active " paratroopers " parachuting everywhere

Erigeron japonicus, also known as small tumbleweed, Canadian tumbleweed, tumbleweed, and small white wine grass, belongs to the dicotyledonous plant family Asteraceae, and is an annual or biennial herb. Erigeron japonicus is native to North America. Its plant was first discovered in Yantai, Shandong, my country in 1860. In the following years, Erigeron japonicus frequently appeared in southern provinces and is now distributed throughout the country. The height of Erigeron japonicus is 40cm-120cm, with an erect stem with rough hairs and fine stripes, alternate leaves, and dense capitula in cones or corymb cones. Erigeron japonicus relies on seeds for reproduction, and the seeds are large in quantity and can quickly invade and spread over a large area, but it cannot reproduce asexually in rhizomes and other parts. Erigeron japonicus can produce a large number of achenes, which have a substance called pappus, which is like a large number of paratroopers jumping from an airplane, quickly blown away by the wind, and spread on the plant in the form of a cover. In August 2014, Erigeron japonicus was officially included in China's "Third Batch List of Invasive Alien Species". In recent years, the occurrence area of ​​Erigeron canariensis has increased rapidly in many areas. If it is not controlled in time, it may cause great harm.

Small fleabane (picture from the Internet)

Foreign weeds adapt to local customs and become medicinal herbs

Erigeron can easily invade riverbanks, canal sides, railways, roadsides, abandoned land, and residential areas, and can invade almost all farmland. Due to its strong reproductive capacity and large seed production, it is easy to form a single dominant population, change the pH value of the soil, affect soil fertility, and even seriously affect the yield and quality of crops. Erigeron can also inhibit the growth of neighboring plants by secreting allelopathic substances, destroying local biodiversity and genetic diversity. Erigeron not only competes with crops for fertilizer and light, but also serves as an intermediate host for pests such as cotton bollworms and cotton blind bugs, which is conducive to the reproduction of pests. In North America, Erigeron not only harms orchards and crop fields such as corn, soybeans, and cotton, but is also particularly prone to invading some no-till land, protected arable land, as well as farms and pastures. In China, Erigeron has already caused damage to my country's ecological environment and seriously affected the local ecosystem. Once it is not removed in time or is neglected, it will become a disaster.

Although Erigeron japonicus is an invasive alien plant, it has adapted to local customs and is used as a traditional Chinese medicine in many places. Some studies have found that Erigeron japonicus has anti-inflammatory, hemostatic and diuretic effects, and can be used to treat wounds, swelling and pain caused by arthritis, as well as diarrhea, dysentery, cancer, etc. In addition, Erigeron japonicus has the effect of heavy metal enrichment and can improve heavy metal contaminated soil.

The small fleabane that can be seen everywhere (picture from the Internet)

Arresting the " paratroopers " is urgent

At present, the prevention and control of Erigeron candidum in agricultural and forestry production is still mainly based on chemical methods. Chemical weeding has the advantages of fast speed, less labor and low cost, but it will cause environmental pollution. At present, the main chemical herbicides used are paraquat and glyphosate. Secondly, manual weeding is still an environmentally friendly weeding method worth promoting, including manual pulling and mechanical mowing.

Chemical control of Erigeron candidum (picture from the Internet)

Author: Luo Mingdan (graduate student of School of Life Sciences, Hubei University)

Scientific review: Xu Letian (Professor and doctoral supervisor at Hubei University)

Planning: Zhao Qingjian, Wu Yuetong

Editor: Lu Jingwen (intern)