Wednesday, August 28, 2019

Give Guiltless Goldenrod A Break

common goldenrod and a pollinating Cerceris waspWhile most plants respond to the shorter days of late summer by starting to wind down their business for the season, goldenrod is a “short-day” plant, the kind that is stimulated to bloom by dwindling daylight. It’s a perennial in the aster family, and is widespread across North America. Continent-wide, we have something on the order of 130 species of goldenrod in the genus Solidago.

As one of the most abundant blooms of late summer and autumn, this native wildflower is for many pollinators, including numerous bee species, a vital source of nectar as well as of nutritious pollen. Unfortunately, this latter item has given goldenrod a black eye among many allergy sufferers.

Goldenrod’s showy yellow flowers are in full view along roadsides and in meadows and pastures just about the same time that one of the more intense waves of seasonal hay fever kicks in. So it’s understandable that goldenrod has been blamed for the red itchy eyes, sinus congestion, sneezing, and general histamine-soaked misery that some folks experience this time of year. But it turns out that goldenrod pollen is innocent of all charges.

Goldenrod can’t be guilty because its pollen is heavy. That’s a relative term, I suppose, since it’s light enough that bees manage to cart away loads of it. But in the pollen realm it weighs a ton – and also is very sticky – and doesn’t blow far from the plant. It’s not that goldenrod pollen is incapable of eliciting an allergic response, it’s just that to do so, one would have to literally stick it in one’s nose and snuff it up.

Not only is goldenrod guiltless of allergic assault, it has been used as an alternate source of rubber. Henry Ford was intrigued by goldenrod, and reportedly produced some tires made from the plant. Interest in goldenrod was revived during World War II. Goldenrod is also used in herbal medicine to help treat kidney stones, sore throats and toothaches.

So who is to blame for the spike in late summer allergies? The culprit is goldenrod’s cousin, ragweed, although it doesn’t behave at all like its golden relative. I suspect we all have a relative or two like ragweed in our extended family. Ragweed, another native plant, is also in the aster family. But unlike goldenrod it churns out loads of very light pollen.

It is so light that ragweed pollen can remain airborne for several days. In fact, significant quantities have been found in the air as far as 400 miles out to sea. And a single ragweed plant can produce a billion pollen grains to fly on the breeze and make you sneeze. Yep, that’s the stuff that stuffs you up.

One reason we don’t suspect ragweed is that its blossoms are dull green and look nothing like a typical flower. It’s as if they’re trying not to attract attention, staying under the radar and letting goldenrod take the rap. The reason ragweed is easy to overlook is that it is wind-pollinated, and therefore has no need to advertise with bright colors and sweet nectar to attract pollinators. Wind-pollinated plants have discovered it’s a lot easier to attract wind than bees, but the downside is they need to make lots more pollen.

Most ragweed species – there are about 50 of them – are annual, but come back each spring from the copious seeds they produce in the fall. Ragweed will continue to churn out allergens until the first hard frost, so let’s hope it is not too much of an extended season this year. And please help to spread the word about goldenrod to spare it any more false accusations.

Photo of common goldenrod and a pollinating Cerceris wasp courtesy Hardyplants at English Wikipedia.

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A Canton, NY-based arborist, educator and writer, Paul Hetzler had intended to be a bear when he grew up, but failed the audition. He settled for an educator position instead, and serves as Horticulture and Natural Resources Educator at Cornell Cooperative Extension of St. Lawrence County.

His work has appeared in the medical journal The Lancet, as well as Highlights for Children Magazine. He is the author of Shady Characters: Plant Vampires, Caterpillar Soup, Leprechaun Trees and Other Hilarities of the Natural World.

You can reach Paul at the Cornell Cooperative Extension office in Canton at (315) 379-9192.




3 Responses

  1. Dana says:

    Paul,

    I advise against giving goldenrod much of a break in your pollinator garden. It spreads like – well – a weed!!

  2. Ott says:

    I once thought my wife was a weed, but I found she was a good pollinator, so I kept her anyway

  3. Michael McHale says:

    Paul,
    Thanks for setting the record straight.
    I think I might plant some goldenrod in my butterfly/pollinator garden for next year.
    Michael

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