What is a weed? Naturalist explains how weeds are defined

The reign of the Lawn King has been challenged and there is rumbling among the masses.

Both lawn loyalists and turncoats alike fired comments and questions in the wake of my recent column on native landscaping.

In that column I questioned the dominant paradigm of the American lawnscape. The ensuing e-mails and conversations boil down to one fundamental inquiry: What is a weed?

Let's start with reader Thomas Buscaglia's questions as we launch into the choppy waters of the debate. Tom asked my opinion of Queen Anne's Lace.

"Is it a weed or a natural wildflower," he queried, "and if (it's a wildflower) is it allowed to flourish on one's property? And how do people with allergies live with other neighbors who have 'natural lawns' but don't know the difference between a weed and a (native) flower?"

Tom's questions cover a lot of territory centered on our underlying question. The most stripped-down version of the definition is: A weed is a plant that is in the wrong place. Makes sense.

But my immediate riposte is, "Says who?" Or, look at it this way: Queen Anne's lace, a lovely plant with cream-colored bouquets of lacy flowers, hails from Europe. Does it belong in a North American cornfield?

According to a farmer, no. Does it belong in a native prairie? According to a plant ecologist, no. Does it belong in your garden? If you make flower arrangements, maybe. Does it belong in the ditch along the roadside? If you like a touch of beauty in an landscape blighted by McDonald's' wrappers, Starbucks' cups, and old Nikes - yes.

According to our first definition, the answer is always a value judgment and the human-in-charge gets to make the call.

Taking another approach to the question, a weed may be defined as an aggressive plant that competes with cultivated plants. This definition has an agricultural spin. For example, Amaranthus (aka, pigweed) is a weed to both farmer and gardener. It bullies its way into field and flower bed to the detriment of corn, soybeans, marigolds and petunias. But how does Tom's example of Queen Anne's Lace fare by this definition? Farmers herbicide it, bouquet collectors cherish it, natural foodies harvest it. Once again, the answer's up for grabs.

A third definition is one I learned as a botany student at the University of Illinois. This definition takes the concept of weed a slightly different direction. According to Dr. Almut Jones, professor emerita who mentored me through Field Botany, a weed is a pioneer plant that thrives in disturbed conditions. "Pioneer" refers to a plant that moves into an area quickly and establishes itself in a short amount of time. An ecological disturbance is an abrupt change caused by natural or man-made events. Examples of the former include tornadoes, floods, and earthquakes. The latter includes herbicide and turf grass.

With all the nuances in these three definitions of a weed, how's a person to know if a plant is truly a weed or not? Here's where the government comes to the rescue - maybe. The Federal Noxious Weed Act of 1974 defines a noxious weed as "any living stage ... of a parasitic or other plant of a kind which is of foreign origin, is new to or not widely prevalent in the U.S., and can directly or indirectly injure crops, other useful plants, livestock, poultry or other interests of agriculture, including irrigation, navigation, fish and wildlife resources, or the public health."

The Act is slanted toward agricultural interests - and it plays the citizenry card as well. Under this definition, a nonnative plant that gets in the way of agribusiness can earn the nefarious "noxious weed" title. But on the state level, there are native plants that are labeled as noxious weeds, and there are "naturalized" nonnative weedy plants that have been here so long that their origins are obscured.

Despite the indecisive nature of the argument, there are some generally agreed upon traits of weeds. The more easily a plant grows, the weedier it is. The more aggressive a plant is, the weedier it is. The more common the color of the flower - say, white or yellow - the more likely are people to label it a weed.

Weeds also tend to be annuals and biennials, completing their life cycles in one to two seasons. Another common characteristic of weeds is that they are particularly well adapted to areas of human impact. Weeds grow where we live and hardly anywhere else.

In essence, then, we invented the weed. Kind of makes you wonder if a weed is all a figment of human imagination. Put another way, if a plant grows in the forest and no one is there to see it, is it a weed?

Weeds are weeds only according to us. Weeds are a product of civilization.

Now, to the second part of Tom's question: If Queen Anne's Lace is a weed, is it allowed to flourish on one's property? And will it lead to endless sniffling and snuffling and watery eyes? The answer to both is: It depends!

To address the question of allergies, I visited several Web sites of common allergens and spoke with friends and relatives with allergy problems. People can be allergic to just about anything under the sun, it turns out - and people can be allergic to the sun itself. There's a wide spectrum of botanical suspects in allergy cases, and fauna are accomplices to the crime as well. Unfortunately, all native plants seem to be guilty by association with anything that causes an allergy in one or more humans.

Let's look at two kinds of plants that cause tearful misery to many: the oak tree and ragweed. Both are native. Both are wind pollinated. Both produce copious quantities of pollen and send allergens to the four corners of the earth. Both are impossible to avoid in their flowering season. Which is a weed? Which is not?

You guessed it: ragweed is the weed. A noxious weed, no less. The state of Illinois says: If you've got it, get rid of it. Oaks, on the other hand, produce prodigious pollen but are not noxious weeds. In fact, the white oak is Illinois' highly acclaimed state tree. So in your native garden, thumbs down to the ragweed, but two thumbs up for the oaks.

As for the question of whether or not Queen Anne's Lace and her associates are allowed to flourish, we have to go to the books. Homeowner's associations have restrictions on landscaping. There are regulations on city, county, and state levels as well. And at the top of the pecking order is the Federal Noxious Weed Act.

Listing a plant on the noxious weed roster is a federal declaration of war. Chemical and biological arsenals are unleashed and the battle begins. The opposing troops, however, are tenacious and resilient, as Carl Sandburg presaged long before the 1972 Act.

"There are laws in the village against weeds," Sandburg wrote in 1922. "The law says a weed is wrong and shall be killed. The weeds say life is a white and lovely thing. And the weeds come on and on in irrepressible regiments." From Carl Sandburg's poem, Weeds, in his book of poetry, "Smoke and Steel.")

Queen Anne's lace keeps on coming, ragweed keeps on coming, along with chicory and curly dock. Fellow troopers include goldenrod and blazing star, Indian grass and bluestem, vervain and violets. You decide. Noxious or nice? Beauty or beast? When it comes down to it, a rosinweed by any other name would smell as sweet.

<p class="factboxheadblack">Goldenrod: An innocent bystander</p> <p class="News">Any discussion of plant allergies must include Goldenrod, a classic example of misguided ire. Goldenrods grow profusely in fields and forests, flowering in earnest come fall. Why hasn't anyone declared war on these noxious weeds? Well, because they are not noxious weeds.</p> <p class="News">There are some 15 species of goldenrods in Kane County, most of which are highly desirable native plants. None of the goldenrods is wind pollinated. Goldenrod flowers are insect-pollinated and thus bear heavy, sticky pollen that is transported via the hairy legs and fuzzy abdomens of little flying creatures. </p> <p class="News">The only way you can get goldenrod pollen in your nose is for an insect to fly from a goldenrod blossom straight into your nose. Or, I suppose, you may rub your fingers on the flowers and then put your fingers in your nose. But the chances of these two scenarios are slim. </p> <p class="News">So, when you see those plumes of golden yellow flowers, relax, breathe deeply, and enjoy these colorful bouquets in the autumn woods and fields.</p>