Yellow Willow Sapling

A decorative tree and nothing more. It grows and cuts down like any other forest tree, so plant it because you want the drooping yellow canopy in a build, not because it does anything for you.

The Zoologist stocks it once your Bestiary is reasonably filled in, which puts it behind general play rather than any particular boss. They are cheap enough to buy a whole row at a time. If you later decide you wanted pink instead, Shimmer converts it into a Sakura Sapling and back again, so the choice is not permanent.