This small plant flowering in my shade garden is Cimicifuga, or more commonly known as Bugbane. Despite its name, the perennial isn't toxic to bugs, but the leaves give off an odor that repels them. However, butterflies flock to the blooms. Bugbane can grow up to 6 or 7 feet high, but may take a few years to get established. I planted this one about 8 years ago. It lay dormant through the drought and only flowered for the first time last year. I'm hoping this fall blooming plant really takes off now.