Black Snakeroot. Height: 4-7 Feet Spread: 3-4 Feet partial-full shade. In the fall, the long bottlebrush flower spikes of this plant give it its height and erect form. It performs wonderfully when planted as a woodland border as it is very shade tolerant. Divisions can be made in early spring. Plant goes well with: Rodgersia, Ligularia, Astilbe, gold-leafed hostas and ferns. has very dark, purplish-black leaves and pinkish-white blossoms. resists deer and rabbits.