Mimosa pudica is a small plant, often classified as a weed, that is pretty common around Texas. Its claim to fame, and the reason that so many kids love to see it, is that it has the unusual property of being touch-sensitive. If you run your finger down the middle of one of its compound leaves, the individual fronds will fold upwards towards one another. You can read more about this fascinating plant on Wikipedia.
I shot this out at the Lady Bird Johnson Wildflower Center yesterday morning during a couple of hours satisfying my macro photography craving. The little flower here is about 3/4 of an inch across. For thos interested in more technical details, I used 56mm of extension on my 28-300mm lens and a Nikon R1C1 macro flash with two flash heads enabled at 10 and 2 on the ring, one set 1 stop below the other.
For the technically inclined...