Field Guide

An invasive native of Eurasia that is spreading in Missouri, musk thistle is a plant you should know. Learn how to tell the difference between our native thistles and these bad guys.

Bull thistle is a weedy introduction from Europe, found statewide. To tell it from our other thistles, note its stems with spiny-margined wings, and its leaves with the upper surface strongly roughened with stiff, spiny bristles.

Tall thistle is a native thistle that can grow to be 10 feet tall! To identify it, notice its leaves, which are unlobed (though they may be wavy or have only shallow, broad lobes), are felty-hairy beneath, and have prickles only along the edges.

Canada thistle is a native to Eurasia and arrived on our continent probably before the Revolutionary War — most likely mixed in agricultural seed. A bad weed of crop fields and rangeland farther north, it causes problems in Missouri, too.

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

“It’s an odd plant,” this rattlesnake master, “with its leaves like yucca, a head like a thistle, and second cousin to the carrot.” That’s how the great prairie writer John Madson summed it up!

Cacti make us think of the desert southwest, but there is at least one species native to Missouri. This prickly pear grows in glades, sand prairies, rocky open hillsides, and other dry, sun-soaked areas.