Green Side Up

Garden talk with Gazette community blogger Janice Peterson.

Don't blame hay fever allergies on goldenrod

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Janice Peterson
Monday, September 23, 2013

This is the time of year when masses of beautiful yellow goldenrod flowers appear along roadsides and in meadows. It is also the time when nasal allergies can really kick in. It may seem logical to assume goldenrod is the culprit of those allergies, but this isn't the case. The real culprit is ragweed, which hides behind a bland exterior while letting a flashier, albeit harmless plant take the blame.

Ragweed and goldenrod both thrive in sunny spots such as ditches, pastures and meadows, and flower from late summer to early fall. Goldenrod (Solidago spp.) has large sticky pollen that is designed to be carried by insect pollinators. Its pollen is mostly too heavy to be wind dispersed. The flowers of ragweed (Ambrosia spp.) are inconspicuously small and green. Ragweed produces copious amounts of small-sized pollen that are easily dispersed by wind. The pollen is so adept at traveling by wind that it's been found hundreds of miles out to sea! Ragweed is considered the primary cause of hay fever.

The Latin name for ragweed, Ambrosia, means “food for the gods or immortality” which perhaps describes how difficult it is to eradicate this plant once established. There are several species of ragweed. Two often seen here in Wisconsin are common ragweed and giant ragweed. Both have deeply lobed leaves that look ragged (hence the name) and have hairy stems. Common ragweed grows about three feet tall while, as the name suggests, giant ragweed can reach 13 feet tall.

Solidago means “to make strong and healthy”; goldenrod has been used as an herbal remedy by healers including Native Americans. Wild goldenrod grows between three and five feet tall, and has dense, plume-like panicles of bright yellow flowers. Goldenrod is the state flower of several states including Kentucky and Nebraska. And for a bit of phenology, children know that when goldenrod blooms it's time to return to school (and if they don't know that someone should teach it to them).

Goldenrods are beautiful additions to the fall garden and many perennial cultivars, including dwarf varieties, are available to the home gardener. They are unfortunate victims of mistaken identity and do not deserve the bad rap they get for causing hay fever. Blame ragweed instead! Now excuse me while I get some Kleenex and a Claritan.

Janice Peterson has worked as a grounds horticulturist at Rotary Botanical Gardens in Janesville since 2002. She is a master gardener with the Rock Prairie Master Gardener Association. Though her education is in plant science, she considers her love of gardening and strong back to be her true qualifications. Janice is a community blogger and is not a part of The Gazette staff. Her opinion is not necessarily that of The Gazette staff or management.

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