Sweetly medicinal aroma gives this Mentha away

I could be accused of featuring plants in the mint family too often, probably. It is definitely one of my favorite plant families. This week, we have yet another member, and I think you'll agree that it is worth a thought or two.

This is a perfectly good member of what we traditionally call the mint family (Lamiaceae. An alternative name for the family is "Labiatae," and you may see this in your wildflower guides, too. This is actually an old, classical name for the family, but it is just as legitimate and legal as the name "Lamiaceae." Use either one for the mint family, and you won't be wrong.).

First off: Everything in Lamiaceae is not "mint," that is, the stuff that goes in your iced tea and has such a memorable aroma. The various species of true mint all belong to the genus Mentha. There are LOTS of other genera in the family, most of which contain species that don't look anything like "mint."

Indeed, members of the family commonly have some very interesting smells. Think of sage, lavender, rosemary, basil, which all have very characteristic, pleasing scents. Of course, other members have a decidedly stinky fragrance.

Whether pleasing or stinky, the aromatic scents in the mint family generally come from tiny, glandular hairs on the stems and leaves, releasing volatile compounds into the air, and onto other things, if rubbed or touched. You've probably heard that members of this family have square stems — in cross section. This is generally true, but, of course, there are various degrees of squareness that you'll come across.

One constant attribute of everything in this family is the way the member species make their seeds. Each flower has the potential of producing four dry nutlets, no more. Each nutlet has a single seed inside.

Our Mystery Plant is common all over the Southeast, growing as an annual in a variety of habitats. It is most commonly seen in dry situations: woodlands, rocky outcrops and open fields are good places to look. This species has a broad distribution and is well-known to plant fanciers, hikers and naturalists from Texas into eastern Canada. It grows to be couple of feet tall, often producing lots of branches. The leaves are bright green, stalked and sort of football-shaped.

To me, the plant's foliage yields a prominent, sweetly medicinal mintiness. It's not the sort of thing I would want in my tea, nor would it be very good in a salad, probably. Nevertheless, it is a strong, pleasant smell.

What usually strikes people even more is the way the flowers present themselves. Although small, they are stupendous. A two-lipped, green calyx is present. Then we have a wonderful corolla of five fused petals, usually deep blue, forming an upper and lower lip. The lower lip often has a pale area with a number of dark purple spots. Even more impressive are the four wonderful stamens, elongated and prominently curling downward, nearly into a circle.

This week's Mystery Plant: "Blue curls," Trichostema dichotomum.

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