Field Guide

White snakeroot looks very similar to thoroughworts, but it has triangular leaf blades that are more broadly angled or rounded at the base. White snakeroot is common statewide. It’s a toxic plant if eaten, so it’s good to be able to identify it.

American, or common boneset has small, white flowerheads in flat-topped clusters at the top of the plant. The leaves are hairy, narrowly triangular, and in opposite pairs fused around the stem.

A stout perennial that can grow to 6 feet tall, tall thoroughwort is a member of the sunflower family that has dull white flowers and distinctive leaves that are opposite, slender, very short-stalked, and with three quite noticeable veins.

Mist flower, or wild ageratum, is a vigorous native perennial bearing fluffy-looking, bluish-purple flowerheads. It looks quite a bit like the annual ageratum that is sold as a bedding plant in garden centers.

Yellow crownbeard and its close relatives are called wingstems because of lengthwise, winged ridges along the stems. Look for it blooming, May through October, in open and rocky areas.

Called carpenter’s weed for its remarkably square stems, cup plant is also notable for its large, opposite leaves that fuse around the stem to form a leafy cup that holds rainwater.

“Infestation” is the term for what teasels are doing in Missouri. Learn to identify these thistlelike plants, and help to control the weedy spread of these tough, prickly invaders.

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.

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.

Leaf cup is named for the leafy appendages that wrap around the stem at the bases of the opposite leaves. Part of the sunflower family, leaf cup has about 8 white ray florets surrounding yellow disk florets.