Field Guide

Indian hemp is a shrubby, upright perennial with opposite branches and milky sap. This native plant can be a troublesome weed in crop fields and gardens, but Native Americans used its tough, fibrous stems for rope-making.

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.

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.

Naiads are slender, narrow-leaved plants that grow completely under water and are rooted to the bottom. They never have broad, floating leaves or conspicuous flowers or seed heads.

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.

Narrow-leaved vervain is a short, slender perennial with single stems or with upper stems sparingly branched. Its many small flowers are crowded on narrow spikes. The corollas are tubular, deep lavender or purple, with 5 spreading lobes.

Sometimes called wild oregano, dittany, like true oregano, is a member of the mint family and can be used as a culinary herb and in teas. Look for it on dry, wooded slopes in Ozark counties.