Mystery Plant! #736
Posted 8/17/23
By John Nelson
johnbnelson@sc.rr.com

Such a wonderful Mystery Plant this week: a real treat for the eyes, as well as the nose.
It’s a native member of the mint family, starting to bloom about now, in the late summer. It is somewhat woody, especially toward the base, the sort of plant you might call a “subshrub”. Of course, the leaves are opposite, like everything in the mint family. Its foliage is characterized by a strong, musky sort of sweetness. A number of aromatic compounds are made in the leaves and stored in the various glands present on the leaf surface. (This is where the fragrance comes from.) It’s a very characteristic, smoky scent, and to me doesn’t smell like anything else. Definitely not “mint”…some people will say it’s stinky, and certainly not minty, as in that green stuff that goes into your iced tea. This brings up a matter about understanding plant families. Sometimes when we botanists speak of the mint “family”, listeners sometimes infer that all the members of the family are “mint”, which isn’t so. The mint family, of course, is a huge one, with many thousands of species. The true mints are members of the genus Mentha. Referring to a plant family by its common name, such as “mint” family or “sunflower” family is a bit troubling to a stickler like me, who would prefer using the scientific names, Lamiaceae, and Asteraceae, respectively. Why, you could (and can) just as easily refer to the mint family as the “basil” family, just like the sunflower family could be, and sometimes is, called the “dandelion” family. It’s just that the scientific name of the family removes all doubt as to what is being discussed.

Anyway, our Mystery Plant has its flowers borne in a series of compact, rounded heads situated at the top of the flowering stem. At the base of each of these heads, there are a number of very conspicuous pinkish bracts, and these are heavily dotted with tiny golden-yellow glands. The flowers themselves are showy and creamy yellow: the corolla is tubular, with a very dramatic upper lip, this arching over the lower lip. Inside the corolla tube will be two long stamens. The slender style, which is forked at its tip, can be found in there, too. All sorts of insects love the flowers…bees, butterflies, and wasps are frequent visitors. Hummingbirds, too. I have found myself, a number times, standing in a big population of this plant on a warm afternoon, marveling at the interest being shown by all the pollinators: it can be an impressive sight. And sound.
This species is widespread in eastern North America and the Southeastern states, and then well west of the Mississippi River. In the East, it’s most commonly seen in the coastal plain, and in the Midwest, it’s a prairie plant, usually on sandy or rocky soil. It’s starting to bloom now, and sometimes you can find big patches of it. It has a number of relatives, such as “bee balm” and “bergamot”, most of which are very attractive and useful in gardens. .
[Answer: “Spotted horse-mint,” Monarda punctata]
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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 www.herbarium.org or email johnbnelson@sc.rr.com.
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