Missouri ironweed tags in with a flourish to relieve fading summer perennials, offering up a vivid display of fluffy, magenta flowers that attract and feed numerous species of insects. Dark green, lance-shaped leaves alternate along sturdy stems that culminate in showy panicles of rayless flowers from mid-July to September. Although ironweeds are not commonly used in domestic gardens, word is spreading that the perennial is nearly unbeatable in the number and variety of insects it attracts. To sweeten the deal, deer and other mammals dislike the bitter-tasting foliage. Currently listed as endangered in Ohio, Missouri ironweed is easily grown in full sun or light shade and is adaptable to a range of moist to average soils. It grows in a clump and spreads via self-seeding and rhizomes that form offsets to create a small colony of plants. Deadheading can reduce the amount of unwanted seedlings, but it also removes a food source for late-season song birds. Missouri ironweed is an excellent choice for pollinator and rain gardens, meadows, and naturalized areas. If the plant's stature is undesirable in a smaller setting, cut it back halfway through the growing season to reduce the ultimate height.

Missouri ironweed and giant ironweed (V. gigantea, also known as tall ironweed) are very similar in form and function and readily hybridize in places where their ranges overlap. Both have tough, rigid stems that remain standing well after flowering, a trait that is thought to have inspired the common name. Vernonia derives from the English botanist William Vernon.

Ironweeds are often swarming with members of an oligolectic bee species, denticulate long-horned bee (Melissodes denticulatus), that only collects pollen from plants in the Asteraceae family. The solitary ground-nesting bee needs ironweed as a food source to successfully rear its young, and it carries loads of the plant's uniquely white pollen on the fluffy region (scopa) of its hind legs. The insect is easy to identify due to its unusual coloring--black with gray hairs and brilliant-blue eyes.

Habitats include moist to mesic black-soil prairies, openings and edges of woodlands, swamps, edges of lakes, overgrazed pastures, vacant lots, and areas along railroads. It's common in disturbed areas and is also found in high-quality habitats. It pairs well with other late bloomers and grasses, such as goldenrods, sunflowers, asters, Indian grass, switchgrass, and big bluestem.

Plant Characteristics:

Grows 3-6' tall.

Prefers full sun or light shade.

Grows in moist to average soils, including loamy, clay, and slightly gritty. Somewhat drought tolerant.

Flowers bloom for over a month between mid-July and September. At the apex of the plant, inflorescent clusters of flower heads consist of rayless composite flowers. The hairy stems of the inflorescence are usually reddish brown. Each composite flower is about ½–¾" across and has 30 or more disk florets. There is no floral scent. Ribbed, slightly hairy achene (single seed within a hardened wall) has small tufts of light brown hair for wind dispersion.

Alternate, lanceolate, dark green leaves are up to 7" long and 2" wide with slightly serrated margins. Undersides of leaves are covered in dense white hairs, which are longer and more prominent than other Vernonia species.

Stout central stem is covered with fine white hairs. Root system is densely fibrous and rhizomatous.

Reproductive System: Male and female parts are on the same flower (perfect/bisexual). The plant also reproduces vegetatively (asexually) through rhizomes.

Wildlife Value:

Host plant for larvae of parthenice tiger moth, red groundling, and ironweed borer moth. Members of the genus Vernonia support the following specialized bee: melissodes denticulatus. Visited by bumble bees, Epeolini cuckoo and miner bees; monarchs, swallowtails, whites, sulfurs, painted ladies, and other butterfly species. Bee flies and halictid bees may also visit. Mammalian herbivores avoid consumption of this plant because of the bitter taste of the leaves.

Medicinal, Edible, and Other Resources:

Native Americans used ironweeds medicinally, mainly as a pain reliever.

Lactones extracted from an African species of Vernonia have been shown to inhibit tumor formation.

Resources:

Buckeye Yard and Garden Online

https://bygl.osu.edu/node/2227

Chicago Botanic Garden

https://www.chicagobotanic.org/sites/default/files/pdf/plantevaluation/no45_vernonia.pdf

Chicago Flower Club

https://www.facebook.com/groups/chicagogardens/posts/3695527400601365/

Go Botany

https://gobotany.nativeplanttrust.org/species/vernonia/missurica/