Hybridized from a famous American wildflower, the spiderworts are wonderful perennials for moist, shaded spots.
The wild form of this unique three-petaled flower is usually purple, and grows along streams. That tells you to give them plenty of water and some shade. The foliage is lily-like, forming a clump of glossy green.
The botanical name tells you the history of this perennial plant. It's called Tradescantia after John Tradescant, a famous English plant explorer who visited North America during the colonial period and "discovered" this native perennial flower.