Mystery Plant! #726

John Nelson

Posted 6/7/23

By John Nelson

(Photo by Linda Lee.)

Mint, sage, rosemary, thyme, horehound, mountain-mint, catnip, bee-balm, marjoram, pennyroyal, lemon-balm, hyssop, lavender, dittany and basil (is it BAY-zil or BAAA-zil?): what an aromatic bunch of plants these are! All of these are fragrant members of the widely distributed “mint” family, one of the larger families of flowering plants, with five thousand (or so) different species. This family is known correctly by either of two different names, Lamiaceae or Labiatae, so don’t worry, if you prefer saying “Lamiaceae,” [lame-ee-A-see-ee] someone using “Labiatae” [lay-BEE-uh-tee] in the conversation will know what you mint. (Oops, I meant “meant.”) Whichever name you use, this family is rather easily recognized in most cases, its component members having opposite leaves (two at a time) and square stems (in cross section). In addition to the culinary value of this family, many of its members are well-known as popular garden ornamentals. The fragrance (or in some cases, the skunkiness) associated with various members of the mint family usually comes from volatile oils maintained in tiny glands on the surface of the leaves and stems. There are some other characteristics shared by members of this family. For instance, the calyx and corolla are variously tubular, with the flower containing four stamens. (True sage, in the genus Salvia, is an oddball, with only two stamens. The shrubby “sage” or “sage-brushes” in the cowboy movies are actually members of the sunflower family.) The fruits of these plants are tiny, dry, one-seeded nutlets, and each flower’s ovary has the potential of producing a maximum of four of them.

Botanists sometimes refer, offhandedly, to members of this family as “mints.” It’s good to remember, though, that everything in the mint family is not mint. What we call “mint” and what often ends up in juleps and iced tea, belongs to the genus Mentha (there are several dozen species). Similarly, it’s also good to know that everything in this family is not fragrant or aromatic. Our Mystery Plant is one of these.

It’s an attractive, perennial species, native to Europe and Asia, but is now widespread in much of North America. Here in the Southeast it is frequently seen along roadsides and under powerlines. It grows to be a couple of feet tall, and has narrowly egg-shaped leaves. There will be a dense cylindrical mass of flowers at the top. The corolla is flamboyant, strongly tubular and upturned, flaring out at the top into an upper and a ragged lower lip. Corolla color is generally deep purple or bluish, although white-flowered forms are occasionally encountered. Bees like them. After the flower is pollinated, the colorful corolla will eventually wither and fall away, leaving the calyx, and of course, there will be those 4 little nutlets inside.

Now if you use your imagination, the open flower might resemble a gaping mouth, perhaps like someone saying “Ahhh” at the doctor’s office. Can you see why people sometimes have used the plant as a gargle for sore throats? 

[Answer: “Heal-all”, Prunella vulgaris]

John Nelson is the retired 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 or email

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