SHIZUOKA - Weeds, often seen as symbols of toughness and perseverance, may in fact survive not because they are strong, but because they have developed highly efficient strategies that avoid unnecessary competition and maximize their chances of reproduction, according to recent research.
The latest installment of the science program focused on a familiar but often misunderstood subject: weeds. Many people associate weeds with resilience, believing they can grow anywhere and continue thriving no matter how often they are removed. The popular Japanese expression "weed spirit" is commonly used to describe someone who endures hardship and keeps fighting.
However, Shizuoka University Professor Hideo Inagaki, a leading researcher on weeds, says that image is largely incorrect.
Inagaki, a professor in the university's Faculty of Agriculture and the author of more than 150 books on weeds, argues that the traditional understanding of "weed spirit" does not reflect how weeds actually survive.
"If people imagine weeds as recklessly pushing forward and working harder than everything else, that's wrong," Inagaki said.
According to the professor, the primary goal of any plant is to flower and leave behind seeds. From that perspective, repeatedly using energy to stand back up after being trampled is inefficient. Instead, weeds focus on producing flowers and seeds even under unfavorable conditions.
"The real weed spirit is not getting back up every time you're stepped on," Inagaki explained. "It's continuing to flower and leave seeds behind even while being stepped on."
He said weeds never lose sight of their ultimate objective, a lesson that may also apply to human life.
Another surprising finding is that weeds are not particularly strong competitors. While they may outperform cultivated plants such as vegetables, flowers, or lawns, they are often weak compared with many plants in natural ecosystems.
"Weeds cannot survive in deep forests," Inagaki said. "They are plants that escaped from competition."
Rather than fighting stronger plants head-on, weeds have evolved strategies that allow them to thrive in places where competition is reduced, including urban environments and disturbed ground.
Their survival tactics can be remarkably sophisticated. One example is a weed known as michitane-tsukebana, whose seed pods burst open when disturbed. When people pull the plant from the ground, the force of the action helps scatter its seeds over a wider area. Some seeds can also attach themselves to clothing, allowing humans to unknowingly transport them to new locations.
"In a sense, the plant is using human behavior," Inagaki said.
Weeds also maintain large reserves of seeds in the soil, waiting for favorable conditions. When gardeners remove weeds, sunlight suddenly reaches the soil surface. For many weed species, light serves as a signal that competing plants have disappeared and that conditions are ideal for germination.
Unlike many vegetables and flowers, which sprout after being buried in soil, numerous weed species use exposure to light as the trigger to begin growing.
As a result, removing weeds can sometimes encourage more of them to emerge.
"The more you weed, the more weeds increase," Inagaki said. "For weeds, that's exactly what they want."
The research suggests that weeds have survived not through brute strength, but through flexible, efficient strategies that prioritize reproduction, exploit opportunities, and adapt to uncertainty—traits that have made them some of the most successful plants on Earth.
Source: テレ東BIZ
