Genus - Epimedium
Epimedium are also called barrenwort or bishop's hat. It's name derives from the Latin Epimedion. The common name of barrenwort comes from the mistaken belief that it causes sterility. The name bishop's hat drives from the shape of the flower, sillier to a bishop's mitre. There are over 60 species in the genus. they flower in shades of white, pink, rose, red, violet, and yellow. Cultivars available today are most often used as a ground cover in shady areas. Epimedium is deer resistant.
Culture - Grows well in full or part shade. This is one of the few plants that will grow well in dry shade. If is dry the plant will spread more slowly. For those spots where you need a ground cover under a tree epimedium will do the trick. Epimediums spread through creeping underground roots called rhizomes. As you can see from the photo below they can become quite dense.