Yes, some herbs are trees. Two familiar ones: juniper and willow. The berries of the juniper tree (Juniperus communis) have been eaten to treat rheumatism, fight indigestion, and flavor gin, while the tree itself was grown beside the door to repel witches. (Think of that while you sip your next dry martini.) The bark of the white willow (Salix alba) has been used for centuries to relieve pain. Its active chemical, salicin, was the first source of salicylic acid--the precursor of aspirin.