A Brazilian species known primarily not from its occurrence in the field but by its commonality in the horticultural trade. The photo on the left shows what I think to be an example of enantiostyly in Ruellia…. some flowers open with the upper style and stigma pointed to the right, and some to the left. A cool evolutionary story centered around reproductive outcrossing, if so.
The photo on the right shows a very interesting structure that our colleague Mariette Manktelow named “the filament curtain” in 2000. It is what it sounds like… each pair of filaments fuses to the corolla wall near the mouth, and forms a protrusion which continues all the way to the base of the corolla. All Ruellia have a filament curtain — in fact, almost all Ruellieae do (thus, it is synapomorphic for the tribe – see Tripp et al. 2013, International Journal of Plant Sciences). Currently, its function, if it has a function, is unknown. Hypotheses include floral stabilization, prevention of nectar evaporation, or some other function during plant pollination. See another example of the filament curtain under Ruellia bourgaei.
Not vouchered, cultivated (RSABG and DUKE Greenhouses); Photo by Erin Tripp