Field Guide

In Europe, St. John’s-wort was long used as a medicinal herb and to ward off evil magic. Today, researchers are finding it can treat depression. Yet it poisons livestock and in some places is an invasive weed.

Missouri’s cattails are all tall wetland plants with narrow, upright leaves emerging from a thick base, and a central stalk bearing a brown, sausage-shaped flower spike.

Three species of yucca grow wild in Missouri. Spanish bayonet was introduced from the Southwest and has escaped from cultivation, but our two soapweeds are native.

Compass plant grows to 8 feet tall and has foot-long, deeply cleft leaves at its base. It got its common name because its leaves turn so that the surfaces face east and west to take full advantage of the sun’s rays.

Of Missouri’s six rosinweeds, prairie dock is identified by its large, leathery, unlobed leaves, which are nearly all in a basal whorl. Only a few small leaves grow on the stem.

One of the worst invasive species in the world, Japanese knotweed can thrive in many places and can even damage foundations of buildings — not to mention the harm it causes in natural habitats. Learn to recognize it so you can prevent its spread.

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.

A spiny annual with bright yellow flowers and dandelion-like leaves, buffalo bur is an introduced member of the nightshade family.