Before the turn of the century, eighty-five percent of Iowa's land was covered by prairie. Pioneers traveling through the state saw a wide range of colorful native plants. Today, the Iowa Department of Transportation is attempting to reacquaint travelers to Iowa's prairie heritage with plantings of native vegetation along roadways. Below is a list of some native plants that a motorist might notice in bloom at this time of the year. The Iowa Department of Transportation publishes a colorful brochure with photographs of native wildflowers and grasses that have been planted along Iowa's roadsides.
Prairie Sage (Artemisia ludoviciana) is found in sandy soils and full sun. This plant is frequently seen throughout the state. Heights range from 1 to 3 feet. The aromatic stems are covered with grayish hairs. Greenish-white, non-showy, tubular flowers are produced in August and September.
Partridge Pea (Chamaecrista fasciculata) (left) is an annual found throughout the state along roadsides and in dry, prairie remnants. It prefers dry soil and full sun. Heights vary from 6 to 36 inches. The finely cut leaves fold together when touched and also at night. The partridge pea produces bright yellow flowers with red to purple anthers from July through September.
One might see the white to slightly pink daisy-like flowers of Daisy Fleabane (Erigeron annuus) from late spring to October. Its toothed leaves have numerous hairs. Heights range from 1 to 5 feet.
Rough Blazing Star (Liatris aspera) is a prominent member of the tallgrass prairie. It is commonly found in the eastern two-thirds of Iowa. Blazing star prefers sandy soil and full to partial sun. Stiff hairs appear on the 2-to 3-foot stems. Leaves get progressively smaller as one goes up the stems. Spikes of pinkish purple flowers appear from late July into September. Flowering begins at the top of the spikes and progresses downward.
From July through August, clusters of pink to lavender, tubular flowers appear atop the square, aromatic stems of Wild Bergamot or Horsemint (Monarda fistulosa). This plant does well in dry conditions in a wide variety of soils. It does, however, prefer full sun. Horsemint is widely distributed across the state.
The individual flowers of Evening Primrose (Oenothera biennis) (right) only last one day, opening in late afternoon to dusk. The blooming period occurs from July through September. Plant heights range from 1 to 6 feet. The foliage is spear-shaped. Evening primrose is most commonly found in eastern Iowa along roadsides, in disturbed areas, and in prairie remnants.
Yellow Coneflower or Gray-headed Coneflower (Ratibida pinnata) is found along roadsides and in dry, prairie areas throughout the state. It prefers full sun. Plants are 2 to 4 feet tall with a rough texture. The leaves and stems have hairs. Coneflowers bloom from July through August. The flower consists of pale yellow petals (actually ray flowers) which droop downward and a center cone. The center cone is composed of disk flowers, which are initially gray but turn brown upon opening.
Another native plant with daisy-like flowers is Black-eyed Susan (Rudbeckia hirta). It is found throughout the state but is rare in western counties. Black-eyed susan prefers full to partial sun. The 1-to 3-foot-tall plants are coarse and have leaves and stems covered by rough hairs. The flowers appear July through August. They have golden petals (ray flowers) with brown centers (disk flowers).
Compass Plant (Silphium laciniatum) is common throughout the state. It prefers full sun and is tolerant of a wide variety of soils. Plant heights can range from 3 to 12 feet. Stems are bristly and exude a resinous juice. Its irregularly lobed leaves tend to orient themselves in a north-south direction, hence the common name. Yellow, daisy-like flowers appear from July through August. Both the ray and disk flowers are yellow.
Hoary Vervain (Verbena stricta) prefers full sun. Plant heights range from 2 to 3 feet. The stems are slightly squared. Both the stems and the coarse, egg-shaped leaves have whitish hairs. Hoary vervain's purple to rosy pink, spike-like blooms appear from July into September.
Ironweed (Vernonia fasciculata) is scattered throughout the state but appears infrequently in most southern and western counties. It prefers full to partial sun. Heights range from 3 to 5 feet. The stems are red-purple and wiry with narrow leaves. Numerous deep purple, flat flower heads occur from July through September.
The blooms of Culver's Root (Veronicastrum virginicum) resemble white or lavender candelabras. These blooms occur in July to late August. Culver's root is infrequently found in northwestern parts of Iowa but is common elsewhere. It prefers full to partial sun and reaches heights of 3 to 7 feet. Leaves are spear-like and whorled around the stem.
As you travel across Iowa on various vacations and trips this summer, enjoy the many plantings of native grasses and wildflowers along the state's roadways.
This article originally appeared in the August 21, 1998 issue, pp. 113-114.