The weeds in our gardens are as specialized as the plants we grow for flowers and fruit.
Most weeds, like cultivated corn or Bartlett pears or giant dahlias, cannot be found in the wild. Their development and spread may be traced to the explorations and migrations – and farm and garden projects – of human beings.
“My Weeds: A Gardener’s Botany” (Houghton Mifflin; $11.95), by Sara Stein, will give you a new outlook on weeds. Of the more than 200 common weed species in the United States, almost half may be used for food, medicine, twine, dye, soap or pillow stuffing. The other half are ornamental plants, such as Japanese honeysuckle and blackberry, which may be sold in nurseries, but whose beauty is tempered by their aggressive growth.
Virtually every weed in North America originated in Europe or Asia, arriving on the ships and in the seed pouches of the settlers who came here to live. In the 17th century, ships arriving on the eastern seaboard carried ballast in the form of soil that contained dandelion, plantain, bindweed, and crabgrass seeds. When the ballast was dumped to make room for return cargo, these weeds happily took up residence in the New World.
About 150 years ago, North Dakota was settled by farmers from Russia. In the sacks of wheat they brought with them were seeds of tumbleweed, given its name because, when it dies, it is easily uprooted and blown by the wind, tumbling across the plains. It seems ironic that tumbleweed – linked in the mind with stagecoaches and symbolic of the American west – should actually come from the Steppes of Asia.
One of the most unfairly maligned plants is the dandelion. Stein points out that it is highly nutritional, with nine times the vitamin C and 42 times the vitamin A of iceberg lettuce. As in the case of lettuce, once the dandelion produces flowers, its leaves are too bitter to eat. However, dandelion flowers may be fermented into wine, and dandelion roots used for a tonic and a magenta dye.
Stein did extensive research on herbicides. She came to the conclusion that Round-Up, whose active ingredient is glyphosate, is the safest herbicide; you would have to drink 22 quarts of the standard spray solution to have a 50 percent chance of dying. Glyphosate kills weeds by interfering with their ability to make proteins. Compared with the lethal effects of some Los Angeles weeds, glyphosate is hardly a health threat. Jimsonweed, castor bean and Queen Anne’s lace, which can pop up in anyone’s garden, cause severe illness or death if their seeds, leaves or roots are eaten.
Although Round-Up is the most popular herbicide, with sales in excess of $1 billion each year, it is not a perfect product. Glyphosate is a nonselective chemical, which means it kills anything that’s green.