In addition to the rare and wacky, and even on occasion the very showy, one of the things I enjoy most about botanical excursions around the country is seeing species that I'd previously never heard of in genera with which I am familiar. The plant that is the topic of this post fits that description. This is Houstonia serpyllifolia (aka Hedyotis michauxii), Thymeleaf Bluet. At a quick glance, this species (particularly the 4-merous powder-blue flowers with yellow corolla throats) looks like the Quaker Ladies (Houstonia caerulea) that is widespread throughout the eastern United States. Don't be fooled, though... one must take a closer look, especially at the distribution of leaves on the plant, to know that this is a species with a much more restricted geographical range and habitat requirement than that of Quaker Ladies. On Thymeleaf Bluet, or Mountain Bluet as it is also known, the leaves are tiny and nearly round, and they are distributed primarily on creeping stems from the base of the plant (leading to yet another common name, Creeping Bluet). Quaker Ladies has leaves that are more spoon shaped in a basal rosette and sparsely distributed in an opposite fashion up the stems.
As mentioned above, Thymeleaf Bluet isn't as common overall as Quaker Ladies. In fact, the former is only known from a narrow band along approximately 500 miles of the Appalachian Mountains in nine states; in two of those states on the fringes of its range (Kentucky and Pennsylvania) this member of the Madder Family (Rubiaceae) is a species of conservation concern.
In addition to the foliage differences between Thymeleaf Bluet and Quaker Ladies, you would likely know you weren't looking at Quaker Ladies if you saw this plant simply by observing the habitat in which you were located. Whereas Quaker Ladies grows in open woods, meadows, and grassy areas, Thymeleaf Bluet is found along streambanks and on rocks in streams, in rich woods, on damp slopes, and on spray cliffs in seepage areas.
In future posts this winter, I hope to highlight other plants from our spring foray that I didn't discuss on Get Your Botany On!. Stay tuned!