On my Friday hike in the Shenandoah River Park I came across a flower that was unfamiliar to me. One of my fellow hikers named it Tradescantia and I subsequently learned that the common name is Spiderwort and a very interesting fact. This flower has stamen hairs that when subjected to radiation turn from blue to pink. If examined under a microscope and the individual cells counted that have changed color, the number is directly proportional to the radiation exposure. Olympus [email protected] macro mode, f6, 1/1000s, ISO 800.