|Ruellia brittoniana Dwarf Mexican Petunia|
Started from seed a couple of winters ago, ours bloom intermittently for several months. Those dark green leaves persist for several months
Part of the reason ours bloom so little is that they are in too much shade.
The plants grow a foot tall. They are cold hardy in zones 7 to 10 only.
The plants are host food for the Common Buckeye butterfly caterpillars and the flowers are a nectar source for most local butterflies.
Ball Seed has some interesting information about them. They call them Ruellia Southern Star Pink and also have pink and white flowering varieties.
Outside Pride calls them Southern Star Ruellia and like many references suggests that they can become invasive. Mine have not moved an inch nor sprouted from seed anyplace other than where I placed them two years ago.
The tall, purple flowering variety has been declared a Texas Super Star.
"The dwarf, less-aggressive version of the species is Katie dwarf Ruellia (sometimes called Nolan's dwarf). About 6 inches in height, it works nicely in an informal front-of-the-border grouping or as a groundcover in narrow spaces," said Mackay. "Katie needs no deadheading, and will continue to flower all season long, and is just as tough as its species parent, able to grow in hot, dry neglected spots."
In good soil, the plant will reseed true, but is not as invasive as others in the species. Recently, a dwarf pink version of Katie called BonitaTM was patented and introduced by Color Spot Nurseries.
The Texas Superstar effort is one of Texas A&M University's most innovative and successful horticultural research and Extension programs."
There's a good article about Ruellia at Austin Bug Collection's site http://www.austinbug.com/larvalbugbio/ruellia.html