[Smart Farmers] Why the beautiful Canada goldenrod became the "devil's flower"

Recently, an enthusiastic netizen posted a message on the city message board of Wuhan City, Hubei Province, revealing that he had discovered an important invasive species, Canada goldenrod. The city’s Agriculture Bureau responded quickly and handled the matter properly.

Netizens' city message board messages and replies

(Image source: Internet)

The report of the 20th CPC National Congress clearly stated: "Strengthen biosafety management and prevent and control the invasion of alien species". Preventing and controlling the invasion of alien species is related to biosafety and has attracted attention from all walks of life. In late autumn, we can often see a plant with yellow flowers blooming on the roadside. This plant is Canada goldenrod. Looking at the beautiful flowers in the picture below, can you imagine that it is nicknamed "ecological killer" and "devil's flower" by some ecologists and botanists? In its place of origin, Canada goldenrod is a rare plant that is both ornamental and medicinal. However, after they were successfully colonized in my country, they gradually evolved into an "ecological killer" - "devil's flower".

Canada goldenrod

(Image source: Flora of China)

How to Identify Canada Gooseberry? Where Does It Come From?

How do you recognize the small goldenrod when you see them on the road? First of all, we have several species of goldenrod in our native land, which belong to the same genus as Canada goldenrod. For example, Solidago decurrens , Solidago pacifica , and Solidago virgaurea . These are all harmless native plants. We don't need to distinguish them one by one. We just need to understand the difference between them and Canada goldenrod.

Solidago canadensis L. is a plant of the Asteraceae family of the Campanulaceae order. It is also known as yellow warbler and goldenrod. It is a perennial herb with long rhizomes. It can reach a height of 2.5 meters. The leaves are lanceolate or linear-lanceolate, 5-12 cm long. The capitula is very small (4-6 mm) and grows on one side of the inflorescence branch. Most of the curved inflorescence branches and the capitula grown on one side form an open panicle inflorescence. The bracts are linear-lanceolate, 3-4 mm long. The marginal ligulate flowers are very short.

Canada goldenrod

(Image source: Flora of China)

Canada goldenrod is native to North America. It is a perennial herb with the largest distribution in the northeastern United States and Canada. It has now become an invasive plant worldwide. So far, it has spread to most European countries, Asia, Australia, New Zealand and other regions. It can grow from hillside woodlands to swamps, and is commonly found in urban and rural wastelands, beside houses, abandoned land, factory areas, hillsides, river slopes, no-till land, roadsides, railways, farmland edges, and green belts.

Distribution of Canada lily around the world

(Image source: Chemistry Biodiversity )

What harm can Canada goldenrod cause?

As a perennial herbaceous horticultural plant, Canada goldenrod has been widely distributed in my country since it was introduced as an ornamental plant to Shanghai, Nanjing and other places in 1935. It has a large number of seeds and a high survival rate of seed germination. It can quickly form a seedling population in wasteland or disturbed environments and spread rapidly, becoming a common weed. For example, studies have found that a small group of 6 plants can evolve into a large population of more than 1,400 plants in 8 years. They have significant negative impacts on many ecosystems (such as farmland, wasteland, grassland, forest, etc.). According to statistics, once the plant successfully invades orchards, it can cause 10%-30% economic losses, 5%-15% in nurseries, 3%-15% in vegetables, and even cause some economic crops to fail.

Canada flower on the roadside

(Image source: Internet)

The large-scale growth of Canada thistle will also lead to the reduction of ecological niches and diversity of many native species, causing serious negative impacts on local agriculture, forestry, animal husbandry, fishery and related industries. It has become one of the important factors threatening my country's native biodiversity and ecological environment. What's more serious is that it will even endanger human health and social economy; with the rapid development and growth of the global economy, international trade, tourism and transportation industries, its harm is also increasing. Therefore, it has been registered as one of the most dangerous alien invasive plants in China.

Why is Canada thistle so hard to beat in invaded areas?

Canada goldenrod has three characteristics: first, it has strong reproductive ability, combining asexual and sexual reproduction methods; second, it has strong propagation ability, and can be spread by seeds through the wind, and can also be spread horizontally through rhizomes; third, it has a long growing period. When other autumn weeds wither or stop growing, Canada goldenrod remains lush, with yellow flowers and green leaves, and its underground rhizomes continue to spread horizontally, constantly devouring the territory of other weeds, at which time other weeds are no longer able to compete with it.

These three characteristics make it a serious threat to native species wherever it goes, and it is easy for it to become a single Canada goldenrod growing area, causing a direct reduction in the yield of many economic crops. In addition, Canada goldenrod can also release allelopathic substances to inhibit the germination of seeds and seedling growth of other plants, thereby inhibiting native plants and posing a serious threat to biodiversity.

With the accelerated development of global economic integration, the invasion of alien species around the world is showing a rapid growth trend, but it is far from reaching saturation. "This is not only the current situation in China, but also the current situation in the world." The successful invasion of alien species often requires several major stages such as introduction, invasion, establishment and spread. We can establish protection measures at each stage. We should establish awareness of preventing alien invasive species and protecting biodiversity, not buying or releasing plants and animals at will, and become the guardians of ecological civilization together! If you find Canada goldenrod, you should report it to the relevant departments in a timely manner.

Author: Chen Xiaotong (graduate student at the School of Life Sciences, Hubei University)

Scientific review: Xu Letian (Associate Professor and Doctoral Supervisor at Hubei University)