Willow, Salix sp. Salix derived from the Celtic “Sal”, near and “ix” for water. Water, in itself is such a healing element- it is easy to see how willow captures its grace, strength and flexibility just by watching it move with the flow of the surrounding water. Tree medicine in willow is similar to the alder, cottonwood and birch- all contain salicin and all can be found near water with the exception of the Birch which has a more widespread ecology.