Well, it was probably supposed to be Potion Making I, II & III....because I remember seeing potionmaking III, but you needed the impossible achievement (level 61) to get it...and now, they've removed it from the list 'o skills...
Potion Making 3 was in my skill tree this morning - with a prerequisite of Level 61. ;) Now it's gone, but indeed there were eight new skills when the OP posted.
I've heard people say that Rubeweed isn't any good, but I imagine they haven't experimented with it extensively. I grow it exclusively, and definitely see an increase in drops while doing mining runs. My observations weren't very scientifically structured, mind you, but the increases were something like 10 - 11 gems without Rubeweed, and 15-16 with it.