In the Garden
Ralph Purkhiser, Purdue University Master Gardener
I just saw my first goldenrod blooms for the year, and right on time, my eyes are sticky and watering and my nose is running. However, the two events are not really related. It seems that I repeat this explanation annually, but I still hear people saying that the goldenrod gives them hay fever.
To understand the situation, we must discuss the different ways plants are pollinated. Some plants release their pollen into the air and depend on the wind to carry it and complete the pollination process. In other plants, the pollen is carried from one plant to another by pollinators, including insects, birds and other animals. It is those plants that release pollen into the air that cause hay fever symptoms in people.
If a restaurant wants to attract people, the owners put up a sign. Flashing neon signs get the attention of would-be diners. Flowers play the same role in the realm of plants. The flowers advertise the presence of nectar, and as pollinators stop in to eat, they get pollen on them, which they carry to the next flower they visit. Such pollens are generally larger than those released into the air, and usually are a little sticky. Since they are heavy and sticky, they are not released into the air and are not the cause of allergy symptoms. In general, flowering plants do not cause hay fever!
That being said, some people develop specific allergies that may be triggered by the scent of flowers, but such symptoms are specific sensitivities and not true hay fever allergies. Some people also have tactile allergies to the sap of plants, usually resulting in skin rashes instead of hay fever symptoms.
So why does the sighting of the bright yellow flowers of goldenrod signal the start of allergy season? Is it all in our minds? Not at all. It is simply that goldenrod happens to bloom at the same time that ragweed blooms. Ragweed flowers are tiny and green, so they are not showy and advertising for pollinators. They release their pollens into the air and are the major cause of hay fever in the Midwest. Another plant that is air-pollinated is corn. When you see the tassels on the corn, you may find yourself having allergy symptoms. Grasses and many weeds also release pollens into the air, and the beautiful goldenrod gets the blame, because it is more noticeable.
The oft-maligned goldenrod is actually a beneficial plant for the eco-system. In Indiana, there are more than twenty species in the genus Solidago, with one for just about every site. Some tolerate dry soil, while others thrive in wet conditions. Some are only about two feet tall, while others top out over six feet tall. The flowers have many forms, but all have that beautiful bright yellow color to attract the pollinators. The goldenrods are essential for late summer and fall pollinators, providing the energy needed for some to migrate and supplying the food that others need to get them through the winter months.
As noted, the latex sap of Solidago may cause rashes for some people, but that latex has been investigated as a replacement for rubber, and research continues into other possible uses.
Meanwhile, the flying pollen of common and giant ragweed continue to cause watery eyes, runny noses, scratchy throats and sneezing. I encourage efforts to cut or pull those plants before they get to bloom stage. It is not likely that we can get them all, but reducing the numbers will help keep the air clean.