Can't make out the leaves for sure, but looks like one of the native ruellia nudiflora varieties. No rhizome spread as with ruellia brittoniana, but one of the most prolific seed "shooters" I've ever encountered. Robust as anything in sun or shade. Not hard to pull when little, but can leave you hundreds of seedlings wherever you let it roost for a season.

Thank you so much. I thought it would be a ruellia, so I am hesitant to add it to my garden. I did dig one plant up with some root. Here's another image of the leaves. Hope this will help clarify.
Molly

Nice but very, very invasive. Like Bostedo stated, it shoots its seeds like crazy at the minimum touch of water. I let it grow in my garden because I grow weeds but I do not recommend it for a regular garden. Something I like is that it is so aggressive that it would grow in cracks with minimum water, lighting up unexpected places. Something I do not like about it is that it looses its flowers in the early afternoon, like other ruellias...

OK, it does not sound like a plant I would like. There was a time when I thought that I could tolerate invasive plants in my garden, but I now avoid them since they only add to my garden chores and there are plenty of well-behaved plants....so, I feel there is no purpose in bringing thugs into the garden.
Molly

Leaves look right for r. nudiflora. Wise to be cautious. Bill Welch warns they're "nothing more than troublesome and persistent weeds." ... which seems a bit harsh. They will add a lot of weeding work within a typical flower bed or any neighboring lawn space, but have some nice attributes for the right locations.

We keep some as host and nectar plants for several butterflies in an alley border where most of the seeds get washed down the storm drain. As ocgf mentioned, flowers don't last long, but foliage can pass as a very heat and drought tolerant ground cover. Responds well to mowing or trimming to reduce the weedy look. The photo shows a small patch we have in heavy shade at the base of an American beautyberry bush; it flowers only a bit less here than in full sun, so spreading volunteers still pose a challenge.

This post was edited by bostedo on Mon, Jun 16, 14 at 1:09

This is another wildflower a friend has inquired about. Not a very good picture, but that is all I have. It is not like anything I have seen before.