Here is a picture of a wild Alaskan Marsh Violet scattering seed. The picture is a bit fuzzy, but basically, what happens is that the spent blossom is followed by a little ribbed lemon-shaped pod. When seeds are matured, this pod pops open, turning itself inside out and scattering the seeds hither and yon! The same is true of our garden pansies and violas.
To determine how far they can be thrown, bring a viola seed pod into the house and set it on a piece of paper in a warm spot. Chances are by the next morning, the seed pod will have thrown seed well past the piece of paper. When I collect seed pods from my favorite violas, I put a knee-high hosery over the container to keep the seeds from escaping!
Of course, from that point on, I'm sure birds carry them, animals track them around on their feet, and the wind blows them about. Whatever happens, they are always a pleasure to see in the unexpected spots they call home!...WZ