Goldenrod (Solidago sp.) is really at its peak right now, brightening the fading natural landscape of late summer with splashes of yellow in fields, along roadways and on the edges of wooded areas. There are many species of goldenrod and they all have yellow flowers that are produced in late summer to early fall. One common roadside species is Canadian goldenrod (S. canadensis), shown in the photo (if I’ve ID’d it correctly). Goldenrods are in the Asteraceae family and are herbaceous perennials.
Most goldenrods are native to North America and many people consider them weeds but certain species (and cultivars) have been gaining popularity in gardening. Some of the new cultivars are less aggressive spreaders than their wild counterparts and the flowers are very attractive to many beneficial insects including pollinators and parasites and predators of pests. In addition to these nice qualities, goldenrods are considered edible and have been used extensively for medicinal purposes. Commonly assumed to cause allergic reactions when in flower, the pollen of goldenrods is too heavy and sticky to be airborne in large quantities that would be a problem. This time of year, ragweed is the most common culprit.
Medical ailments historically treated using this plant include minor skin wounds, tuberculosis, diabetes, gout, hemorrhoids, internal bleeding, asthma, arthritis, inflammation, high blood pressure and kidney stones. No significant scientific research has been done to date to support these uses but a few laboratory studies do suggest a benefit may occur for inflammation, muscle spasms, fighting infections and lowering blood pressure. It also seems to have diuretic properties. It is used in herbal teas. Consult with your doctor before using goldenrod or other supplements to treat any medical condition. A University of Maryland publication on this subject recommends caution for people that have certain existing health conditions.
An interesting historical use of goldenrod is for rubber. Its leaves typically contain 7% rubber. Apparently Thomas Edison worked on fertilization and cultivation methods to maximize the rubber content and his work produced a 12 foot tall plant with up to 12% rubber content. Henry Ford, a friend of Edison’s, used goldenrod rubber for tires on the Model T he gave to him. Ford also collaborated with George Washington Carver at the Tuskegee Institute, funding work to develop synthetic rubber and/or commercialize goldenrod rubber when World War II caused rubber shortages. Unfortunately, the rubber from goldenrod was not of high enough quality for commercial use.
Traditional garden lore on companion planting lists goldenrod as a plant that seems to attract striped cucumber beetles away from the vegetable garden. No data has proven this one way or the other. Research indicates that goldenrod may have some allelopathic (harmful/inhibitory) effect on some trees, including black locust and sugar maple. Goldenrod has the distinctive status of state flower in both Kentucky and Nebraska and is the state wildflower of South Carolina and the state herb of Delaware.
Goldenrods have been introduced as garden flowers in other parts of the world and in parts of Europe and China have escaped cultivation and become problematic invasives. There are recipes available for making goldenrod oil and vinegar. Whether you use the plant in your kitchen or just enjoy the pretty blossoms, now you know a little more about this native plant and its role in the environment.