In late summer, giant angelica (Angelica gigas) produces immense deep-plum-colored, 8-inch blooms above bold, textured foliage with purple stems that top out at 6 feet. It prefers moist, shady, or partially shaded locations. The blooms are pollinated by a wide range of insects. This stunning specimen plant typically lives for 3 to 4 years. The sap is known to cause allergic dermatitis, and an extract of the roots contains chemicals with coumadin-like (blood thinning) effects that can be fatal.