Viburnum. Fig. 1. Viburnum opulus. Bark of stem.
Cross-section.
This image is from Viburnum prunifolium and Viburnum opulus in August issue of the American Journal of Pharmacy, 1895.
A herbal distance course
Henriette's herbal is one of the oldest and largest herbal medicine sites on the net. It's been online since 1995, and is run by Henriette Kress, a herbalist in Helsinki, Finland.