Floridata - Illustrated informative profile page with notes on culture, usage, and noteworthy features. (zone 4-8) (2 photos)
Missouri Botanical Garden - Plantfinder page for one of the plants growing at the garden, with usually one or more photos, horticultural information, and noteworthy characteristics. (zone 4-8) (2 photos). Also a page for 'Pleniflorum'.
NARGS Image Gallery - Photograph(s) contributed by North American Rock Garden Society members. (2 photos)