A Prairie Imperative—part 2

(He continues with the list of prairie plants found at the Pecatonica Ridge Prairie.)


Rosinweed is a trademark of the prairie. I always look for it and was happy to find it at the Pecatonica Ridge Prairie. Rosinweed is named for its gummy, pine-scented sap. A friend of mine once chatted with a man who had labored on a threshing machine long ago. The old-timer recalled what he would do if the belt began slipping on the threshing machine’s drive pulley; he’d break off a clump of rosinweed and toss it between the drive belt and the pulley. The plants would crush between the belt and pulley—and their sticky sap would make the belt seize to the pulley. Thanks to rosinweeds, the crew could keep on threshing.

New Jersey tea

New Jersey tea is one of the few shrubs that are native to our prairies. This plant has delicate stems and showy white flowers, and it grows to no more than knee-high—so it looks more like a clump of wildflowers than a bush.

The scientific name of New Jersey tea is Ceanothus americanus. Other species of Ceanothus are among the predominant plants in chaparral—the dense, shrubby growth on the coastal mountains of southern California (the backdrop for so many cowboy movies). Chaparral is prone to tremendous wildfires—just like our prairies once were. Ceanothus is adapted to such blazes; both here and in California, the shrub burns away and then grows right back after the fire has passed.

Although New Jersey tea survives and even thrives after being burned up, I have never, ever, seen it growing anywhere except on unplowed soil—in virgin prairies or in savannas that never were cleared and farmed. Once the ground has been broken by a plow, New Jersey tea evidently does not come back—even if the land is allowed to revert to native vegetation.

How could this be? The answer may be underground. Natural prairies are notoriously deficient in nitrogen. Legume plants such as beans and peas can make their own nitrogen fertilizer because they harbor nitrogen-fixing bacteria in their roots. These bacteria extract nitrogen right out of the air and change its chemistry to a form that a plant can absorb through its roots. New Jersey tea is not a legume, but it is one of the few other kinds of plants that have nitrogen-fixing bacteria in their roots.

I wonder: when a prairie is plowed up and all the New Jersey tea is killed, maybe a delicate relationship between this plant and soil bacteria is destroyed. And then, when a surviving seed of New Jersey tea germinates, the growing root cannot find the bacteria that the plant needs in order to thrive and compete with other plants–so the seedling dies. What else could explain why I have never seen this species growing naturally anywhere that has ever been plowed?

Prairie smoke

Prairie smoke is one of the earliest of spring-blooming flowers. The purplish plumes of its seed-heads have been likened to smoke rising from the prairie. This member of the rose family grows on the thinnest soil, where limestone bedrock is right at the surface. The species was first discovered in Illinois in May of 1859 by M.S. Bebb, a physician and pre-eminent botanist who lived near Seward, a few miles south of the Pecatonica Ridge.

Prairie smoke has one of the broadest natural distributions of any species of plant anywhere on the planet. It grows in Newfoundland, surrounded by the waters of the North Atlantic. It grows beyond the treeline in the Yukon Territory, within 500 miles of the Arctic Circle. Its range extends all down the Rocky Mountains into the high-altitude desert of Arizona and even farther south into Mexico. From the Pecatonica Ridge Prairie, you would have to journey more than 1,500 miles to the northeast, well over 1,500 miles to the southwest, and about 2,000 miles to the northwest to seek out the most distant prairie smokes.

Although prairie smoke ranges from Canada to Mexico, the Pecatonica Ridge Prairie is at the very southern limits of its distribution in the mid-continent. This species needs a relatively cool summer climate and limestone soil. Much farther south than the Pecatonica River Valley, it gets too hot, and the limestone is almost all buried by glacial soil.

I imagine that the rocky hilltops around Pecatonica used to turn a hazy purple with prairie smoke each spring. Now there are maybe a dozen of these plants at the Pecatonica Ridge Prairie. If you could climb high up in a tower and look straight south from the Pecatonica Ridge Prairie with an all-powerful telescope, I bet your gaze would not fall upon another prairie smoke plant. But even without a tower and a scope, if you look a little to the east of due south, you can see steam rising from the nuclear power plant on the Rock River at Byron, 17 miles away. A professor from the University of Illinois gathered a specimen of prairie smoke from a “residual limestone hilltop prairie” at Byron on June 16, 1948. Prairie smoke still holds on there today in Jarrett Prairie Nature Preserve.

Little patches of prairie smoke have been found on a few other, scattered spots of dry, rocky or sandy soil farther west in Stephenson, Jo Daviess and Carroll counties. If you stood on the Mississippi River bluff near Galena and peered westward with an all-powerful telescope, you would spy a few prairie smoke colonies in northernmost Iowa—and then you would see no more of them until you focused in on the Rocky Mountain foothills rising beyond Cheyenne, Wyoming!

I’ve shared a little about four plants at the Pecatonica Ridge Prairie: a grass with a seed that plants itself, a flower that links us to the era of steam-powered threshing machines, a shrub that is reminiscent of the California chaparral, and a showy denizen of the northern plains and western mountains. The Pecatonica Ridge Prairie has at least 47 species of native prairie plants, and the lowland north of the prairie has many of these plants plus 32 other native prairie and wetland species. Each has its own story to tell.

Prairies are vanishingly rare in Illinois. One-hundredth of 1 percent of the original prairie has survived in good condition, in about 250 fragments. Each is precious. The Pecatonica Ridge Prairie must be made secure, and then it needs to be cared for. It’s imperative.

This article was prepared for the Natural Land Institute by John White, Ecological Services, 904 S. Anderson St., Urbana, Ill., Edition of June 9, 2005.

From the Oct. 26-Nov. 1, 2005, issue

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