In regards to Spirit...is an inability to benefit from Healing really a drawback to someone who can regenerate even back from the dead?
As for Salix, pollen clouds are fine, I think. Confuse probably isn't the best choice though, for reasons Victim explores a bit. Coughy itchy irritant pollen could be Nauseate or even Stun perhaps...both good incapacitators with no lasting damage done. I'm not as big a fan of teleporting through plants...it feels more fantasyish to me (says the player of the witch

); hard to phrase in terms of modern day 'science.' As a magical effect, that's one thing, but how else would it be explainable? Growing and animating plants could be cool if you like...infected them. Little gas-powered pods that you shoot out into trees and things that link the infected plant to your consciousness.
It's worth pointing out that Salix isn't a druid, isn't a nature-lovin' tree-huggin' guy. He's an alien plant. It'd be cool if his powers reflected that alienness. Like, maybe he blooms flowers with wide crystalline petals, that expel the clouds of pollen. Maybe the color of the flowers change with his mood? Color, odor...these are things about Salix that his kind might use to communicate that could emphasize his nonhumanity. Consider too some Extra Limbs (roots/tendrils/etc). Perhaps a limited Morph that lets him emulate terrestrial plants (in lieu of emulating human beings).
If you want to go even farther in the, "Uh, hey...that's kind of weird and disturbing" direction, consider a ranged transform from Human Into Plant Minion. You shoot a little spore pod into a person, instead of a tree. They break out in fungus and grassy growths and become shambling slaves to your will! Rah!
...probably not. Might be cool if an evil one of your kind ever finds his way to Earth though.
*wink to the GM*