2. Bartonia virginica (L.) Britton, Sterns, & Poggenb. (Virginia bartonia, Virginia screwstem)

Map 1869

Stems 5–45 cm long. Leaves 0.9–4.5 mm long, mostly opposite. Calyx lobes 0.5–1.5 mm long. Corolla lobes 2.5–5.0 mm long, oblong, rounded at the tip, sometimes with a minute sharp point or somewhat irregularly toothed. 2n=52. July–September.

Uncommon, known thus far only from Ste. Genevieve County (eastern U.S. and adjacent Canada west to Wisconsin and Louisiana). Mossy sandstone ledges.

Bartonia virginica is an inconspicuous species at its western geographic limit in Missouri. It was first collected in the state in 1993 by Bill Summers, and may eventually prove to be more common in the sandstone drainages of eastern Missouri.