for context, please see Daily Account for Skykomish River E of Goldbar, WA on 5/12. we have seen the extremely invasive scotch broom in large quantities on other field trips and driving along freeways, but here it was not a common plant- there were only a few clumps of it over the whole walk. we learned that only heavy bumblebees can pollinate scotch broom because they have to put their weight on the flower to release the stigma to pollinate it.