Along certain highways and the railroad right-of-way in Illinois, there are plants which are remnants of the old prairie, most of which has been plowed and its flora changed. Usually in plowed prairie soil other plants spring up; the old species die out and frequently the plants taking their place are escaped cultivated plants or immigrants from Europe or Asia. Only in a comparatively few places in Illinois are there plants typical of the ancient prairie habitat. These stand out as distinctively as if they were foreign rarities consigned to a roadside. Instead, they are the original inhabitants.
Ratibida pinnata (Vent.) Barnh.
July - August Prairie roadsides.
Very late in the history of the Ice Age, the Pleistocene, there was much flooded, soggy land as a result of melt-water from receding glaciers. Through the procession of plant succession which took place over many years, the broad lakes filled with plants, and when the long drouth and scaring winds came late in post-glacial times, miles of prairie formed in Illinois. Plants which never had grown in Illinois before, during all its forested interglacial times and more rigorous glacial periods, now moved in from western plains. Among these very likely were the columnar and the prairie coneflowers.
Far more common, inhabitant of most prairie roadsides in Illinois, is the grey-headed or prairie coneflowor. It is a ragged-looking plant with grey-green compound leaves and flowers distinguished by their hard grey cones and drooping pale yellow rays. It blooms in late July and August. Like its rare relation, the columnar coneflower (Ratibida col-umniferd), it has, somehow and forever, the look of ancient prairie country in its blossoming.