Prepped samples of ground leaves (left) and tannin samples mid-extraction process (right). Photos by Iris Garthwaite

Across the Pumice Plain of Mount St. Helens, Sitka willows (Salix sitchensis) make up a major percentage of the riparian (streamside) vegetation. Parts of our research focuses on identifying phenolic compounds called condensed tannins within willow leaves!

Evergreen undergraduates, Lauren Thompson (left) and Maddie Thompson (right) running the condensed tannin extraction and assay. Photo by Iris Garthwaite

Condensed tannins of willow leaves may act as anti-herbivore compounds and make willow leaves less palatable based on their concentrations. The processes of condensed tannin extraction and assay are very long but filled with numerous colorful steps!  

The colorimetric condensed tannin assay results in an awesome gradient of pink! Photo by Madeline Thompson

Phenolic compounds may differ across the Pumice Plain or by plant sex (willow is dioecious!). Leaf chemistry can influence which insects utilize the leaves and rates of decomposition for leaf litter!