Well, the "mint" family, again. This little discussion will hopefully serve to illustrate the point that common names for a plant family sometimes cause problems. In this case, we have the mint family, which in botanical-ese is called the "Labiatae," or, just as proper, the "Lamiaceae." The first of these family names is by far the older, known from antiquity. The word Labiatae refers to the presence of a flower with lips, as in an upper lip and a lower lip; practically everything in the mint family has a flower whose corolla is indeed bilabiate, featuring an upper and a lower lip. Commonly, the upper lip protects the stamens and pistils within, while the lower lip provides a convenient landing platform for busy bees. The more recent name, Lamiaceae, is derived from the modern legalistic protocol of naming a family after what we call the "type" genus. In this case, the type genus for the mint family is Lamium (you've probably seen a common species of Lamium, or purple hen-bit, growing in your yard in the spring). Thus, the modern name for the family is Lamiaceae. The older name is "Labiatae". Both names are synonymous and equally valid amongst botanists.

The other point in all this is that all the members of the mint family, whichever scientific name you want to use, are not "mint," as in the stuff that goes in your iced-tea. (Or julep.) "Mint" is the common name for plenty of species all placed in the genus Mentha, and an aromatic group of species it is. (Of course, lavender, basil, beefsteak plant, sage, horehound and rosemary, all members of the mint family, have wonderful smells, but there are also plenty of species in the family that are stinky, in fact.)

Our mystery plant, though, is not mint, although it IS in the mint family. It's an herb, very widely scattered over nearly all of the U.S. and southern Canada, and while it looks something like mint, it has no minty aroma at all. It's extremely variable, in terms of leaf margin toothiness, and stem pubescence, and because of this variability, various botanists have proposed a number of subspecies or varietal names to accommodate this confusing variability. Most botanists now, though, tend to dismiss this and just think of the species as a single, variable group … with one name.

It likes to grow in rather damp places in woods and thickets, often along creek banks. Thin rhizomes are produced below ground which makes this plant easy to get spread around … sometimes to the point of weediness. The calyx is green and tubular, with five teeth. The corolla is attractive and white, or bright pink, and rather unusual for a member of the family. While the corollas of most members of the mint family have an obvious upper lip, this little herb has its upper lip split down the middle to the point that there is really no upper lip at all. It's the only member of the family that does this. (Photo by Linda Lee.)

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John Nelson is the curator of the Herbarium at the University of South Carolina, in the department of biological sciences. As a public service, the herbarium offers free plant identifications. For more information, visit www.herbarium.org or call 803-777-8196.