I'm trying to make a wand using a greatwood rod however the prerequisites for it's research are not listed anywhere not even on curse. is there any reason for this? It just says - ?

Greatwood requires !PLANTWOOD , you can get that research from scanning Thaumcraft trees.

Everything else needs infusion, and the rest of the wands need the greatwood rod research.
but I can't get infusion because It needs 150 vis to make the matrix and greatwood is the only thing that can hold more than that