The 'Grease' Willow Salix pentandra is a regular component of the riparian ecosystem along our local river. The female catkins hibernate and open in spring to disperse the fluffy seeds, long before leaf-out occurs. Thus the trees are very visible in the otherwise drab springtime landscape. The vernacular name (Norwegian 'istervier', which means grease willow) is ancient Norse and probably refer to the catkins, which do look like clumps of lard or grease at distance. Another possibility is the foliage which is very shiny and covered with a wax-like cuticula.
I shot with the Nikkor 200/4 Ai on my Zf and had to go to lengths to tame all the CA (lateral and axial) caused by the the numerous twigs and branches acting as a diffraction grating (?). About the worst case I've ever seen.