Field Guide

Large stands of wind-pollinated giant ragweed commonly form in disturbed areas, causing late-summer misery in the form of hay fever for many Missourians.

The purplish or brownish disk florets of purple-headed sneezeweed set it apart from our other sneezeweeds, whose centers are yellow. Look for it in moist, open areas, mostly in the southern half of the state.

Tickseed sunflower has flattened black seeds that attach themselves to clothing and pets via two needlelike awns. In flower, it grows in massive displays in moist bottomlands.

Horseweed looks something like a goldenrod, except that the tiny composite flowers are not yellow. Instead, they are cream-colored and rather drab. In Missouri, this plant is especially associated with disturbed habitats and is a troublesome crop weed.

You may not recognize elephant’s foot as a member of the daisy or sunflower family because it lacks petal-like ray florets. Also, it has unusual, doubly compound flower clusters. And how did it get its name, anyway?

Ox-eye daisy, though familiar, is not native to North America. It was introduced long ago from Eurasia. Common in grassy uplands, pastures, fencerows, and roadsides, it can colonize aggressively in the garden.

Our weediest sneezeweed, bitterweed arrived in Missouri in the late 1800s from its home range in Texas and Louisiana. Like our other heleniums, it has domed disks and yellow, fan-shaped, notched ray florets. Unlike them, the leaves are narrowly linear.

Autumn sneezeweed is a late-blooming perennial with conspicuously winged stems. The flowerheads have yellow, domed disks. The ray flowers are fan-shaped, yellow, and notched.

Native to Ozark glades and prairies, tickseed coreopsis has long been appreciated as a hardy garden perennial. Because of its popularity, it has escaped from cultivation and now occurs statewide.

White heath aster is one of Missouri's most widespread and weedy native asters. It grows in uplands, bottomlands, and nearly all habitats in between. It has a shrubby, wide-branching habit, and the stem leaves are thin and needlelike.