This Week's Mystery Plant

One of my undergraduate students is Carrie Hadden, pictured here. She has distinguished herself within our Department of Biological Sciences by winning the "Outstanding Biology Senior" award this year. I'm very happy to have her as a student: she will make a fine botanist.

The other day after lunch, Carrie picked up a little plant growing along the sidewalk, and began tossing it around. The plant will readily stick to your clothing, and of course we all ended up "wearing" some.

Our mystery plant is common all over the United States as a weed. It is a member of a botanical family (the "Rubiaceae"), some members of which are important economically, giving us coffee and quinine, among other things. This peculiar little herb comes up vigorously in the spring, forming bright green, tender mats of vegetation, often in disturbed places. It is blooming now in our area, and easy to find in vacant lots, roadsides, and field edges. The flimsy stems are slender, and square in cross-section. Equipped thus with weak stems, this plant is generally unable to grow upright, so it flops itself around, commonly leaning and sprawling upon other vegetation. Six or eight narrow leaves will be clustered together up and down the stem, forming whorls. The white flowers are quite tiny, each with four petals.

The most interesting thing about this herb is that all parts of it, especially the angles of the stems, are covered with sharp, backward-pointed bristles. These tiny hooks make it very easy for the plant to snag itself onto passing things, cleaving readily onto fur, feathers, socks, sneakers, trousers legs, or even skin (especially hairy skin). These little barbs, present by the thousands, thus act as a natural sort of Velcro, and it makes sense that the plant can spread itself around by this feature. Carrie, the clever botanist, likes to call it "Velcro plant," but it also goes by many other names. It (and its near relatives) has been used to stuff mattresses, and its tiny, dried fruits have been used as a coffee substitute.

Another one of our spring weeds, it makes quite a show for a few weeks, and then all the plants dry up and eventually disappear by early summer. (Photo by John Nelson.)

Photo by John Nelson