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By Staria Vanderpool

Editor's note: The following article is part of an ongoing science series written periodically by faculty members at Arkansas State University and published by The Sun.

Fall is the season when goldenrods dominate plant communities from roadside to forest.

Native plant enthusiasts admire it, but the 10 to 30 percent of Americans who suffer from seasonal allergies triggered by pollen fear it.

For years goldenrod has been falsely accused of producing hay fever since it blooms at the same time as the ragweed -- the real culprit. The small, green inconspicuous flowers of ragweed are overlooked and allergy sufferers blame the more spectacular goldenrod.

But that plant produces a relatively small amount of large, heavy pollen grains that are carried from flower to flower by insects -- not by wind. In fact, goldenrods attract more varieties of insects than just about any other flower with nectar and protein-rich pollen.

Most of the more than 100 species in the goldenrod genus (Solidago) are native to North America, although one species is European. Thirty-two species occur in Arkansas. Some are common, but others are very rare in the Natural State.

Riddell's goldenrod is one of the rare ones, significant because it occurs in rare habitats such as wet prairies, fens and open bogs. Arkansas' largest population is found in the Rock Creek State Natural Area, a fen with the highest concentration of rare plant species in Arkansas.

While many North Americans view goldenrod skeptically, it has been used historically as a rubber source, a dye, and a herbal remedy for numerous diseases. They may be a source of medicinal compounds because of their known bioactive role, although their relative value is still being studied.

Because some goldenrod species cause toxicity in sheep and horses, any medicinal use of goldenrod should be strictly supervised by a healthcare professional.

Unquestionably, goldenrod species are known to provide significant yields of rubber (12 percent), and were once considered as a rubber substitute. Some of the earliest cars were furnished with tires made of rubber from the goldenrod plant, processed in the lab of Thomas Edison.

Aside from their effect on human health and culture, the goldenrod also provides a better understanding of important environmental issues.

At Arkansas State University, my students and I have been studying Riddell's goldenrod to understand how plants respond to rapid climate changes.

When we compare the range of Riddell's goldenrod to the last continental glacier, it shows that most of the modern range was buried under ice until approximately 10,000 years ago. As the glaciers melted and retreated northward, Riddell's goldenrod followed the receding glaciers. In fact, Riddell's goldenrod is still traveling north into Canada.

How has this range expansion affected the genetic make-up of these plants?

The population of Riddell's goldenrod in Rock Creek State Natural Area provides an opportunity to investigate this important question since what we learn about the consequences of rapid migration in plant populations can be applied to modern plants, and can have predictive value for future plant movements.

Our research also allows us to carry the message about goldenrod and pollen allergies to an international audience.

No permits are required to transport goldenrod into the United States from Canada, but we still had to explain to Customs agents on both sides of the border why importing more goldenrod into the U.S. was important.

So this autumn, when our landscapes are brightened by fall wildflowers, take another look at the goldenrod and consider the many aspects of a roadside wildflower-weed in the Natural State.

For more information contact the Department of Biological Sciences at Arkansas State University at biology@astate.edu.

Dr. Staria Vanderpool is assistant professor of botany in the Department of Biological Sciences at ASU.