growing wild in zone 8 north central Florida. Under old live oaks; gets dappled sun & slanting afternoon full sun.

It's a Ruellia. Ruellia caroliniensis I think.

Edited for spelling.

They are usually called Wild Petunias:

http://plants.usda.gov/java/pr...

No Kent, they are completely different. See:

http://plants.usda.gov/java/la...

At first I thought it was false foxglove but that's not it either.

How about, Dyschoriste oblongifolia

http://www.wildflower.org/gall...

Well there you are Jay! And you get the gold star for ID! Thank you. It's a pretty little flower isn't it?
And I thought for sure you would be the one to call this one the moment you saw it.:
The thread "I know this but can't remember it" in Plant ID forum

Driving me crazy. I know what it is. I have known what it is. It is common. And I can't find it anywhere in any of the references I've found. For some reason the word "pine" keeps floating around in my memory but I could be remembering something else.

Kent, you might be interested to know ---- Citation DYSCHORISTE OBLONGIFOLIA (Michaux) Kuntze, Revis. Gen. Pl. 2: 486. 1891.
Basionym: Ruellia oblongifolia Michaux 1803.