Both of our species have few but rather showy pink-violet to blue-violet flowers in nearly sessile or short-stalked terminal or axillary clusters.
1. Calyx lobes narrowly linear, up to 1 mm broad at base and ca. 15–30 times as long; leaves with spreading hairs (much longer than any minute strigose ones), especially on main veins and margins.
R. humilis
1. Calyx lobes lanceolate, ca. 3–6 times as long as broad; leaves with minute usually ± strigose pubescence.
R. strepens
All species found in Ruellia
Citation:
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. May 21, 2022. https://michiganflora.net/genus.aspx?id=Ruellia.