Silphium Perfoliatum - Very rare, this stately multi-stem bush grows to 6 feet tall. Hardy to –25 degrees C, this native of eastern North America likes damp locations but adapts well to drier conditions. The large angular leaves have toothy margins that form cups with the stem. Covers with daisy like yellow flowers all summer. This is a sun lover and an excellent back of border addition. The roots are medicinal with restorative properties and were used by native Americans in the form of tea to treat fevers, liver issues and ulcers. Pre-chill the seeds in early spring to break dormancy. Then plant in pots cover lightly with soil and place in a warm location.