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Field & Street



The last of the late-season wildflowers are fading. The petals have already dropped from the sunflowers. Only a few of the goldenrods retain the bright yellow of September. Even the asters, always the latest of our fall flowers, are past their prime. If you want to see the last of summer you had better get out this weekend. Next week at this time the only color in the landscape will be the turning leaves.

I got seriously into the fall wildflowers of this region over the course of the past month. I took a class called Fall Flora, offered under the combined auspices of the Field Museum and the Morton Arboretum and taught by John and Jane Balaban of the North Branch Restoration Project. John teaches at Saint Ignatius; give him a chance to conduct a class and he will lay on the rigor in true Jesuit style. Our plant list for this course included nearly 100 species. I thought I had a lot to learn when I signed up, and John and Jane let me know I was right.

We took three field trips during the course, one each to Bunker Hill Woods, Harms Woods, and Miami Woods. All three of these sites have been under active management for 10 to 15 years, and they all show the benefits. The sites were chosen because a fairly rich flora had survived there for 175 years. New species have since been planted, and existing plants are no longer suppressed by heavy shade and fire starvation. Here were places where we could actually see 100 species of wildflowers in a morning--and not just one or two specimens, but populations, abundances of flowers.

I did know a fair number of the species on our class list before I enrolled. But I was looking for a chance to systematize my knowledge, and I wanted to learn more about a few common genera that I knew only incompletely. I had a special interest in the genus Solidago, the goldenrods, and the genus Aster.

Goldenrods are everywhere around Chicago. They grow in the most pristine natural areas and in the median strip of the Eisenhower Expressway. The golden yellow of their flowers is one of the most characteristic colors of late summer and early fall. They are unfairly blamed for hay-fever symptoms that are actually caused by ragweed. Ragweed is a wind-pollinated plant that scatters huge quantities of pollen grains into the air. Some of them reach the ovaries of other ragweed plants; many of them reach the nasal membranes of afflicted animals--including humans.

Goldenrods are pollinated by insects. In fact, goldenrod flowers are good places to look for interesting ones. Soldier beetles--long, slender insects variously patterned in yellow and black or orange and black--are abundant on goldenrod flowers. From what I have seen, goldenrod flowers are the place that soldier beetles go in search of love.

Goldenrods all belong to the genus Solidago, which is almost certainly of North American origin. There are only a few species in Eurasia and South America. The eighth edition of Gray's Manual of Botany, by M.L. Fernald, lists 75 species and several common hybrids in the region bordered by the Atlantic coast, eastern Kansas, southern Canada, and Kentucky. Swink and Wilhelm, in Plants of the Chicago Region, list 21 native species and one introduced.

Real knowledge of goldenrods is one of the key distinctions between those who actually know things and those with only a superficial acquaintance with the natural world. For me, studying goldenrods is an attempt to overcome my deeply ingrained urge to be a dilettante by actually learning something.

Asters offer a similar opportunity. Fernald lists 67 species, some hybrids, and a number of distinctive subspecies. Swink and Wilhelm list 26 and 2 introductions. If I can get beyond the kindergarten level of "that's an aster" or "that's a goldenrod" I will have accomplished something.

There is more to it than that of course. Plants bring information with them. The presence of a particular species tells us something about a place. If we can't recognize the species we lose the information. Swink and Wilhelm have digitized this idea. Every plant in their encyclopedic compendium has a number called a "coefficient of conservatism." The number is a measurement of the tendency of the plant to grow only in relatively undisturbed, stable natural communities. The scale runs from zero to ten. Zero is reserved for opportunists like ragweed. If we find ragweed growing somewhere, about all we can say about that place is that there must be some dirt present. Hairy aster, Aster pilosus, is a zero. Aster ericoides, heath aster, is a five. It is usually found in prairies. If we come across this plant we can suspect that we are looking at a prairie remnant, and we might start hunting for other species typical of that sort of community. If our search turned up some Aster laevis, a nine, we could begin to suspect that we had discovered a prairie remnant of rather unusual quality.

We could verify that suspicion by looking for other plants on the Balaban's fall list. We might find the tall, waving plumes of Indian grass, one of the dominant plants of the tall-grass prairie and a five on the Swink and Wilhelm scale. On a really rich site we might find Sporobolus heterolepis, prairie dropseed grass--a ten--a plant that can survive only on the richest, least disturbed remnants of native prairie.

There are bits of this sort of community at Miami Woods. When this prairie was discovered 15 years ago, these species were embedded in a matrix of weeds. Now the remaining weeds are embedded in a matrix of prairie plants. And down among the grasses are the most stunningly gorgeous of the fall flora, the gentians. Swink and Wilhelm list seven species of gentians in our area. The lowest value is an eight. At Miami Woods and Bunker Hill Woods these beauties are all over the place. One of the gentians is pale yellow, but all the rest are a rich royal blue that leaps out at you as you scan the ground.

Fringed gentian has four broad petals spreading horizontally from a deep-blue cup. Bottle gentian flowers are closed and kept that way by a white membranous cap. Only a strong bumblebee can force its way in to capture the pollen of this plant.

The woodlands of northeastern Illinois are naturally open, rather sunny places where enough solar energy reaches the ground to support the growth of wildflowers that bloom in late summer and early fall. Where woods have been left unmanaged, the deep shade often kills off these species. At Harms Woods we could see elm-leaved goldenrod and blue-stemmed goldenrod growing with blue cohosh, white baneberry, and Short's aster. This was a late-season woodland where a hungry butterfly could have found a meal of nectar from many sources.

If you have no interest in trying to interpret the natural landscape, knowing the difference between tall goldenrod and Short's aster may not seem worth the effort. But I think we desire to learn things in order to make some sense of the world. When we look at nature we can be overwhelmed by all the simultaneous stimuli that hit us. There are so many different kinds of plants, and while we try to sort them out, grasshoppers are leaping about and butterflies are fluttering by and dragonflies are zooming past and birds are calling. To the extent that we can sort out all these impressions, we alienated, atomized, postmodern people can feel at home, connected to something beyond ourselves.

Here in Chicago we can take lessons from the Balabans, who took lessons from Floyd Swink and Gerould Wilhelm, who took lessons from May Watts, who studied at the University of Chicago under Henry Chandler Cowles, one of the founders of the science of ecology. We can enjoy the riches of life in one of the world's great metropolises and still connect ourselves to the natural world.

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