Cut weeds a break: They're just trying to repair your soil

We whack them, we rip them out, we poison them. We ask how to get rid of them, but never why they are there. But weeds have a purpose. Richard Mabey, author of Weeds: In Defense of Nature's Most Unloved Plants, explains.

Lynne Rossetto Kasper: Who makes this decision -- who stands on high and decides this plant is a weed and that plant is not a weed?

Richard Mabey (Elizabeth Orcutt)

Richard Mabey: I think everybody has made that decision at some stage in their life about any plant that got in their way. The first weeds only happened when human beings began cultivating plants. In choosing a plant that was going to be domestically desirable, you automatically, even without thinking, created the category of plants that were not desirable. When the latter began intruding as they instantly did into the territories that you allocated for the growing of your food plants, then the category of weed was created and the circumstances under which it would flourish were also created.

LRK: Weeds were the first foods of early man?

RM: Yes. But it's a philosophical problem if you go back that early. Let's take it out of the abstract into a specific.

One of the very early crop plants of Neolithic man was a member of the spinach family called fat-hen -- in America, it's sometimes known as lamb's quarters. In the wild, it grows in rich floodplains that are disturbed by flood tides and wild grazing animals. But as soon as those early humans began creating small settlements and enriching them with the manure of their pastured animals, fat-hen moved out of the wilderness to grow very close to humans.

It was immediately noticed and began to be used as a crop plant, both for its leaves, which resemble a spinach, but also for its large, mealy seed heads, which were made into early flours and gruels. We're talking about 5,000 years ago at this point. Fat-hen or lamb's quarters remained a rough crop plant for the next 4,000 years.

But at the point at which better spinach-like vegetables were developed and better plants were producing nutritious seeds, it changed its category into a weed. The plant itself didn't change, but we had made a decision that it was no longer a desirable plant. Ones that were had bigger leaves or grew in a more orderly way -- they were the ones that were desirable. So fat-hen dropped its status and got rebranded as a weed.

LRK: What do you feel the weed has to tell us now?

Weeds

RM: First of all, we need to ask questions of them. I think we need to stop having the simple knee-jerk reflex. Here is a plant that culturally we have called a weed. We don't ask any questions about why it's there, we ask questions about how to get rid of it. I think it would be very salutary if we started asking questions about why it's there because you would then unlock a narrative about the plant in which all human history is entangled.

You would begin to understand that weeds have a purpose. Their purpose in nature is to try and repair damaged ground. They classically only appear on cultivated soil in gardens, farms, battlefields and building sites. Anywhere that human beings have wrecked the soil to do projects of their own, weeds come in and try and repair it.

But there is actually a more immediate and human-centered use. All cultivated vegetables, all cultivated ornamental flowers, began with wild plants. They couldn't exist otherwise. Increasingly plant breeders are finding that the highly overbred cultivars, with a plant like the tomato, are like all highly bred organisms: increasingly susceptible to disease, vulnerable to weather changes in a way that their wild ancestors weren't. Their wild ancestors had to evolve in such a way as to be plants for all seasons.

What plant breeders are doing at the moment is going back to the weeds from which cultivated vegetables originated. They are trying to breed them back into the cultivars to see if they can recapture some of that wild vigor. They have a very practical, modern use at a time when our food stocks are threatened by all kinds of diseases of over-cultivation in their production: being the stock to which plant breeders can return.

LRK: Lessons in flourishing from a weed.