The Nature of Eureka


A smile for smilax

You know these plants, and if you’re like most who live where they live, you may hate them. If you’ve ever walked in the woods in the Ozarks, you trip over them. They tear your clothing. They rip into your flesh as you stumble through the forest. When hiking or clearing brush at your yard’s edge, you talk to these plants – generally in loud expletives. I posted a photo of one online recently and got responses such as: “They’ll rip you -up.” “I see this and hear the song Helter Skelter.” “I was clearing some & they fought back big time.” “Two words – controlled burn.”

We call it catbrier, greenbrier, bullbrier – members of the genus Smilax in the greenbrier family (Smilacaceae). The genus Smilax has upwards of 260 species, mostly tropical with outliers extending in temperate climates. There are 20 species or so in North America (north of Mexico), with 11 species in Arkansas.

Some are herbaceous and die back every winter. Others have persistent woody stalks. They scramble, climb, entangle, clamber, and tear you up with their sharp spines. Botany books covering this part of the country, can’t seem to agree on scientific names, descriptions, illustrated characteristics or keys to identifiable features. In fact, you must turn to a 1944 publication that suggests the best way to identify these plants is to dig-up the roots.

We can call these invasive aliens in the broadest sense, since they continue to spread and invade in an evolutionary slow-motion time scale. They arrived in North America before humans existed. Plant geographers and paleobotanists surmise that this plant group originated in Southeast Asia.

Some species like saw greenbrier or catbrier (Smilax bona-nox) traveled eastward, landing in what is now Latin America millions of years ago. It developed a unique adaptation, first observed in a 1917 issue of the Journal of Genetics – spines on the roots to prevent the starch-rich tubers from being eaten by peccaries.

The common greenbrier or horsebrier (Smilax rotundifolia) has a creeping rhizome with no starchy tuber. With its closest genetic relatives in Europe and the Azores, it came our way via a westward route. Both species are difficult to tell apart without looking at the roots. Perhaps nature put them here to help control the real invasive aliens – humans.