We would like to tell our readers about a charming little book about weeds, by the same name. Weeds: In Defense of Nature’s Most Unloved Plants, by Richard Mabey, contains an eclectic collection of information about the weeds of Britain, their origins, the history of their use–including as medicine, the role they have played in literature, and much more.
First, we venture a definition of weeds, though any definition is likely to be controversial. The concept of “weed” originated with agriculture, some 5,000 years ago in the Old World*, when man began to distinguish between those plants that are edible or otherwise useful and those that are not. And so, plants that are not perceived as useful or turn up in the wrong place, were defined by man as “weeds.”
It’s a shifting concept, because a plant that was useful historically, either because it was believed to be a cure for some malady, or was otherwise useful, might be replaced by some superior remedy. Such a changing concept of the value of particular plants is a central theme to the book as well as to the Million Trees blog. We often invite our readers to consider that much of the current interest in native plants is a horticultural fad that is likely to change in the future as it has in the past.
We also often question the designation of hundreds of non-native plant species as “invasive” in California, a designation that makes them a target for eradication. Mabey’s book about weeds helps us to put this designation into perspective. Britain obviously has a much longer history of trade with its neighbors on continental Europe, which increased the potential for the introduction of non-native species. Yet, despite Britain’s longer history of ecological globalization, Mabey tells us that only about one dozen species of plants are presently considered invasive in Britain compared to hundreds in California.
Mabey defends several of the non-native plants considered as invasive in Britain. He believes that some are merely responding to the disturbance of native vegetation by the activities of man. Nature hates a vacuum. When native vegetation is no longer adapted to the changed soil, water, and air quality conditions created by man, any plant that will grow in these new conditions is preferable to bare ground. Plants—including weeds—help the soil absorb rainwater into the ground which would otherwise run off the land, silting streams and causing erosion.
There is much food for thought in this little book. It invites us to compare our list of nearly 200 plants in California that have been officially designated as “invasive” to a short list of only a dozen plants in Britain. What accounts for this big difference? Different conditions or different attitudes? We don’t know the answer to this question, but we think it is a question worthy of consideration.
* Crosby, Alfred, Ecological Imperialism, Cambridge University Press, 2009