Meet Your Neighbors

Goldenrods:
Autumn gold

The goldenrod could use a good press agent. Not only is it falsely maligned as a common sneeze-causing weed, but it has also been stereotyped, oversimplified, and shoeboxed into being, for many people, one single plant. In truth, the word “goldenrod” should never be used in the singular without a modifier, be it “early,” “showy,” “stiff,” or “tall,” since the Chicago Wilderness region alone hosts 23 species of this plant. Members of the genus Solidago, some goldenrods may look very similar at the outset. But they are all quite different, in both aspect and behavior — from the ubiquitous, forceful, and chest-pounding to the graceful, refined, and rare.

The differences aren’t all obvious though. In 1901, Mabel Wright, who published The Garden of a Commuter’s Wife, wrote that goldenrods “are a byword among plant students, who say that if a botanist is ever condemned to the severest punishment that the underworld can mete, the penalty will be to write a monograph, accurately describing and identifying all known goldenrods.”

But it can’t be that hard. Even without a guidebook, hikers can identify early goldenrod, Solidago juncea, simply by its timing: appropriately, it’s our earliest local goldenrod, sending rich yellow plumes across the prairie as early as the second half of July. It also differs from similar goldenrods by the near or complete absence of hair on the stems and leaves.

Or consider the zigzag goldenrod, Solidago flexicaulis. As the common name suggests, if you’re walking through a healthy open woods and notice a goldenrod with a distinctive zigzag stem, you’re most likely seeing this refined, shade-loving resident.

Two much more brusque inhabitants of Chicago Wilderness — tall goldenrod, Solidago altissima, and Canada goldenrod, Solidago canadensis — may be the goldenrods people think of when picturing autumn fields. Though both are natives, these plants’ creeping rhizomes can take over large areas of disturbed land, making them common invasive plants in restored grasslands, roadsides, and untended fields.

With gracefully arching bluish-tinted stems covered with bright yellow flowers, the blue-stemmed goldenrod, Solidago caesia, adds a splash of brilliance to moist woodlands. Within many oak-hickory forests, elm-leaved goldenrod, Solidago ulmifolia, displays its yellow flowerheads on one side of the stem.

Many goldenrods make their home in Midwestern prairies. Sand prairies nurture old-field goldenrod, Solidago nemoralis, also known as gray goldenrod. This short species, 6 to 20 inches tall, features one-sided plumes of small yellow flowers, as well as grayish and hairy stems. Up from mesic black soil prairie grow the erect, rough, hairy stems of the stiff goldenrod, Solidago rigida. Thomas Edison was said to have tried to make a rubber substitute from its sap.

A particular favorite of photographers, showy goldenrod, Solidago speciosa, hangs out in the sandy black oak savannas and proliferates after a good fire.

But several species of goldenrod prefer to keep their feet wet. Wet prairies support Riddell’s goldenrod, Solidago riddellii, while the calcareous conditions of the fen nurture the large flat-topped blossoms of the finicky Ohio goldenrod, Solidago ohioensis.

Some goldenrods are also known to hybridize. According to the Chicago Botanic Garden’s Susanne Masi, “The one perhaps best known is the hybrid of stiff goldenrod, Solidago riddellii, and upland white aster, Solidago ptarmicoides, which resulted in yellow stiff aster, Aster x lutescens.”

Goldenrods offer the perfect setting to watch a bewildering variety of insects eating, mating, and stalking their prey. The blooming of goldenrod and other fall-blooming plants is a critical event for our local pollinators, the last chance for them to put away reserves for winter.

Goldenrod gall flies owe their existence to Canada goldenrod and late goldenrod, Solidago gigantea, on which they lay their eggs. During winter walks, you may notice swollen lumps on the stems of goldenrods. Known as galls, these typically form when the gall fly larva burrows its way into the stem. The plant then hardens off a chamber around the insect where it will overwinter and pupate. The galls do no harm to the goldenrod. During spring, the adult fly bursts through the wall of the gall, if it’s not first eaten by a downy woodpecker or parasitized by wasps. The parasitic wasps Eurytoma gigantea and Eurytoma obtusiventris often inject their eggs inside these galls, where their larvae hatch and devour the flies’ larvae.

Goldenrods have been prized for years by British gardeners, but these true North American flowers are just beginning to gain acceptance by American counterparts, thanks to recent research about allergies. Contrary to popular belief, goldenrod does not produce hayfever. Its pollen is too heavy and sticky to be carried by the wind. Most hayfever is caused by the fine, light, dry pollen produced by the ragweed, a common weed blooming at the same time as goldenrod.

There are many goldenrods that mind their manners, survive well, and provide reliable fall color, as well as food for wildlife. Being natives, they were born to survive our Chicago winters.

Ecologist Jack Pizzo suggests the following goldenrod species for Chicago-area gardens: stiff goldenrod, old-field goldenrod, and showy goldenrod do well in sunny dry sites. For sunny wet sites, such as rain gardens, try Riddell’s goldenrod and rough goldenrod, Solidago rugosa. Finally, blue-stemmed goldenrod, zigzag goldenrod, and elm-leaved goldenrod will brighten up shady spots, though some warn that zigzag can get unruly. Luckily for urban dwellers with limited gardening space, goldenrods also can be grown quite successfully in containers.

If the names of the many goldenrods become overwhelming, forget about them. Simply enjoy these natural fireworks as we move into the leisurely rhythms of fall.

— Mary Boldan