The third full week in September is celebrated as “Prairie Week” in Illinois. This annual event is the result of a law passed by the legislature. The purpose of Prairie Week is to help people understand and appreciate prairies. Events are held during Prairie Week to make people aware of Illinois’ prairies and how they are important to the history, culture, economy and biology of the state. This month in Kids for Conservation® we are featuring prairie wildflowers so that you, too, can be more aware of the diverse prairies that at one time covered about 22 million acres of our state.
What is a prairie? A prairie is a type of grassland. Prairies usually form on level or smoothly rolling landscapes. Prairies have hot, dry summers and cold winters. Prairie plants have roots that remain alive in the soil through cold, fire and other harsh conditions, sending up new plants above the soil each growing season. The prairie plant parts above the level of the soil die each year after they produce seeds. The dead plant parts become dry and easily burn. Fire is an important part of keeping a healthy prairie habitat. Fires convert the dead prairie plants into nutrients that can enter the soil quickly. They eliminate the thick cover of dead plants to allow new plants to grow freely from either roots or seeds. Fires also help to eliminate trees and shrubs from the prairies. If they are allowed to develop, trees and shrubs change the growing conditions of a prairie and could lead to the development of forests on prairie lands. Fires can start naturally, for example by lightning, or humans can start a prairie fire on purpose or accidentally.
You might think that since a prairie is a type of grassland that it would be made only of grasses. That’s not true, though. Wildflowers (forbs) as well as grasses grow in prairies. Grasses are flowering plants, too, but their flowers are not as showy as those of forbs. Short forbs tend to bloom early in the growing season before they are shaded and crowded by the taller, slower-growing prairie plants that bloom in summer and fall.
Flowers are special to humans. We visit prairies and other habitats to see them bloom. We grow them in our yards. We give them to others to show that we care. What are flowers? Flowers are the reproductive parts of a plant. After the flowers are pollinated, fruits are produced and inside the fruits are the seeds that ensure future generations of this type of plant can exist.
Many prairie wildflowers are members of the aster family (Asteraceae). In these plants, what looks like a single flower is actually a flower head composed of many small flowers. In a typical flower head of the aster family, there are two different types of flowers. The "petals" that are around the edge of the flower head are the ray flowers. In the center of the flower head are many disk flowers. Some plants, like blazing-stars (Liatris) have only disk flowers. Other plants have only ray flowers.
Here are just a few of the wildflowers of Illinois prairies. We hope that you will have a chance to see some of them in bloom this month!
leadplant Amorpha canescens
Leadplant grows throughout Illinois except in the far southern part of the state. This plant is one of the few prairie shrubs, and it is good for prairies, unlike the shrubs we talked about in paragraph two. The flowers are small and hundreds of them are clustered in spikes at the tip of a stem. Only one bright-purple petal is present per flower. The flowers attract bees and wasps. Flowering occurs mostly in June and July.
prairie milkweed Asclepias sullivantii
Prairie milkweed is found in moist-soil prairies throughout Illinois. The rose-pink flowers are produced mainly in June and July. The flower clusters contain 15 to 40 flowers. Many insects visit the flowers, including bees, bee flies, butterflies and beetles. This species provides habitat for the larvae of monarch butterflies (Danaus plexippus), too.
ox-eye sunflower Heliopsis helianthoides
Although its common name is ox-eye “sunflower,” this plant is not a sunflower. This species grows in prairies statewide and can reach a height of two to five feet. Its leaves are arrowhead-shaped and arranged in pairs on the stem. Flowers develop on individual stalks. Up to 20 yellow ray flowers are present per flower head along with many yellow disk flowers in the center. Blooming occurs from June through October.
American feverfew Parthenium integrifolium
American feverfew, also known as wild quinine, grows in dry woods and prairies throughout Illinois. It blooms from June through September. The flowers are white, very small and produced in clusters at the stem tip. The flower clusters look like tiny heads of cauliflower. This plant grows two to three feet in height. Its common name “feverfew” was given to the plant because early settlers used a tea made from its leaves to treat fever.
common mountain mint Pycnanthemum virginianum
Common mountain mint grows in prairies throughout Illinois, although it is more frequently found in the northern one-half of the state. It blooms from July through September. The flowers are white, small and produced in clusters at the stem tip. Only a few flowers bloom in each cluster at one time. This plant has a square stem. Common mountain mint grows one and one-half to two feet in height and attracts a variety of pollinators.
black-eyed Susan Rudbeckia hirta
Black-eyed Susan flowers from May through October in prairies statewide. Each flower develops on a single stem. There are 10 to 20 yellow ray flowers in each flower head around a chocolate-colored center containing many disk flowers. A single plant may reach one to three feet in height. Leaves and stems have bristly hairs.
royal catchfly Silene regia
Royal catchfly grows in dry prairies in parts of eastern, northeastern and southwestern Illinois. A single plant may be two to four feet tall. Flowers are produced from July through August. Each flower is on an individual stalk. There are five red petals per flower at the end of a tubelike green structure. Royal catchfly is endangered in Illinois.
prairie avens Geum triflorum
Prairie avens, also known as prairie smoke, grows in dry prairies in northern Illinois. This species blooms in May and June. Each stem has three to six red-purple, drooping flowers that are individually stalked. The name "prairie smoke" comes from the long, feathery plumes on the seed pods, giving the plant a smoky look. Prairie avens rarely grows more than one foot tall.
butterfly-weed Asclepias tuberosa
Butterfly-weed, also known as butterfly milkweed, is found throughout Illinois, especially in sandy soils. Unlike most milkweeds, the sap of butterfly-weed is clear, not milky. The larvae of monarch butterflies feed on the leaves. The bright orange-red flowers are a rare color for prairie plants. Plants flower from mid-June to mid-August. Many insects visit the flowers.
New England aster Aster novae-angliae
New England aster is found throughout Illinois. A single plant may reach six feet tall. The flower heads, lavender to purple or pink with a yellow or orange center, are produced from August to October. Each flower head is composed of ray flowers and disk flowers. Many different insects visit the flowers, especially butterflies and long-tongued bees.
white wild indigo Baptisia alba
White wild indigo grows in prairie habitats statewide in Illinois. It has one or a few upright stems three to five feet tall with the flower stalk at the tip. All parts of the plant turn black upon drying and can yield a dye. Larvae of some sulphur, elfin and blue butterflies feed on the leaves. Flowers appear in June and July. The flowers are pollinated by worker bumble bees. During the winter, the whole plant breaks loose from the root and rolls along with the wind, scattering seeds.
purple prairie clover Dalea purpurea
Purple prairie clover occurs throughout most of Illinois. It grows to a height between one and two and one-half feet tall. Each stem tip ends in a flower cluster. Flowering starts at the base of the cluster and moves upwards. Flowers have red-purple petals. Flowering occurs in June and July. A wide variety of insects visit the flowers, including bees, flies, wasps, beetles, bugs and butterflies. Some mammals and butterfly larvae eat the leaves.
shooting-star Dodecatheon meadia
Shooting-star occurs throughout Illinois in many prairie types. Each shooting-star plant may grow to one to two feet tall with a single flowering stalk arising from a cluster of basal leaves. The flowers appear from May into early June and hang upside down on the stalk. Flower color varies from white to pink, lavender and bright rose-purple. The petals are positioned backwards, like the tail of a shooting star. Pollination is carried out mostly by queen bumblebees. This species is among the earliest prairie plants to bloom in the spring.
pale coneflower Echinacea pallida
Pale coneflower lives in black soil, gravel, sand and hill prairies throughout Illinois. Each plant is two to three feet tall and usually has only a few stems. One flower head is produced at the end of each stem. The rose-pink ray flowers drop downwards as the flower head fully opens. In the center is a brown-purple structure that contains the disk flowers. Flowering occurs from June to mid-July. Many insects, especially long-tongued bees, butterflies and skippers, visit the flowers for nectar and pollen.
rattlesnake master Eryngium yuccifolium
Found in all regions of Illinois, rattlesnake master grows in a variety of prairie types. Its blue-green color and long leaves with spiny edges make rattlesnake master easy to identify. Each plant has stems three to five feet tall with round flower clusters at the tips. Many small flowers occur in a spherical, bristly heads. Bloom time is in July and August. The silver-white flower heads attract many insect visitors, including beetles, butterflies, wasps and bees.
downy sunflower Helianthus mollis
Downy sunflower is found in most areas of Illinois, except for some northern counties. The plant is covered with soft green-gray hairs. The flower heads have about 12 yellow ray flowers around a center of yellow disk flowers. Each stem often has a single flower head at the tip but may have up to eight flower heads. Maturing in August and September, the flower heads attract bees, bee flies and butterflies.
rough blazing-star Liatris aspera
Rough blazing-star is found in dry prairies in nearly all of Illinois. Ten to 60 flower heads are spaced along the upper stem. The flower heads are lavender-pink. Each flower head contains 15 to 40 disk flowers. The blooming period is August and September. Long-tongued bees, butterflies and bee flies visit the flowers.
hoary puccoon Lithospermum canescens
Hoary puccoon is found in prairies in most of Illinois. The plant is covered with soft, white hairs. Yellow with a touch of orange, the flowers are arranged in a spiral at the tip of the stem that unfurls in an arc as the season progresses. Flowering occurs from late April to June. These flowers are visited by butterflies and long-tongued bees.
wild bergamot Monarda fistulosa
Wild bergamot occurs in nearly every county in Illinois growing in a variety of habitats. A plant may reach two to four feet in height and has square stems. A cluster of bright lavender flowers develops at the end of each stem. Each individual flower is tubular and two-lipped, the lower lip forming a landing platform for insect pollinators. Numerous kinds of insects flock to the flowers, including bees and some butterflies. Peak bloom time is July and August.
obedience plant Physostegia virginiana
Found nearly statewide in Illinois, obedience plant grows in prairies and other habitats. Height varies from one to five feet. Each stem holds a spike of flowers. Flower color varies from soft pink to rose-pink, with darker spots inside. The three lower petal lobes form a landing platform for bees. The broad flower opening is well suited to pollination by bumblebees. Other bees also visit the flowers, as does the ruby-throated hummingbird. The blooming season is mostly August and September.
drooping coneflower Ratibida pinnata
Drooping coneflower is found in almost all Illinois counties, except a few in the southern part of the state. It is most common in dry prairies. This species grows to about four to five feet tall. Each flower head has six to 12 yellow, drooping ray flowers around a central cone of numerous disk flowers. Flowering occurs in July and August. Many types of insects visit the flowers, including bees, wasps, flies, butterflies and beetles.
compass plant Silphium laciniatum
In Illinois, compass plant occurs in almost every county. It has large leaves at the base of the plant that are deeply divided into thin segments. The plant’s stems may reach four to 10 feet tall. The stems and leaves have stiff, white, bristly hairs that are rough to the touch. It is known as “compass” plant because the leaves at the base of the plant are usually oriented in a north-south direction. The yellow flower heads are produced at the stem tip. In each flower head, twenty to 100 ray flowers are arranged around a center of many disk flowers. The blooming season is July and August. Long-tongued bees are frequent pollinators, but many other insects visit the flower heads, including other bees, flies and butterflies.
prairie dock Silphium terebinthinaceum
Prairie dock occurs in all parts of the state, except for the far northwestern section. Prairie dock is the tallest prairie plant, sometimes reaching a height of 10 to 12 feet. It has very large, spade-shaped leaves that only develop at the base of the plant. Two to six yellow flower heads are produced at the tip of the stems. Twenty to 100 ray flowers surround a cluster of many disk flowers in each flower head. The blooming season is July and August. Long-tongued bees are frequent pollinators, but many other insects visit the flower heads, including other bees, flies and butterflies.
stiff goldenrod Oligoneuron rigidum
Stiff goldenrod occurs nearly statewide in most types of dry to moist prairies. Stiff goldenrod has a stout single stem that branches only in the flower cluster at its tip. Arranged along the branches are small flower heads. Around the edge of the flower head are seven to 14 ray flowers surrounding the central disk flowers. Both the disk and ray flowers are bright yellow. Bloom time is August and September. Many types of insects visit the flowers including bees, wasps, flies, butterflies and beetles.
Culver’s-root Veronicastrum virginicum
Culver’s-root grows in nearly every county of Illinois. Many small white flowers occur in “candelabra-shaped” spikes at the stem tip. The whole spike can be more than a foot tall. Bees, wasps, small beetles and some butterflies collect nectar or pollen from the flowers. The peak blooming season is in July and August.
Classification and taxonomy are based on Mohlenbrock, Robert H. 2014. Vascular flora of Illinois: A field guide. Fourth edition. Southern Illinois University Press, Carbondale. 536 pp.