And Jenbrink, they come in several colors and sizes. I have a small one (under a ft. tall) that stays small and has very delicate, pale pink flowers. Another that gets way over a ft. tall and has deep blue to purple flowers. The tiny pink one is a lady and behaves herself, but the blue/purple one goes nuts and tries to take over. Google "Hardy geranium" pictures and check out the possibilities. barb
chedderpink, it seems you're referring to Geranium species in general... Geranium sanguineum does have a low-growing pink variety (var. striatum) but the species doesn't have blue flowers. It is rhizomatous, categorically, but I haven't found it to be invasive at all (seeding seems to be more responsible for its spread)... I'm guessing your blue-purple flowered invasive one is another Geranium species, some of which are pretty rampantly-spreading. Anyway, no question... "hardy geraniums" (Geranium spp.) are a great group of garden plants, with a large number of garden-worthy species and hybrids.