Oh yeah. I forgot that one because you can't apply Primordial Giant to a Petal. (The race I was using in this instance)
It wouldn't be worth the LA hit, but you could turn it into a Half-Troll, then apply the Primordial Giant template. As a DM I use that template all the time to make things into giants. Of course, I'm working in a Norse world, where trolls are rather common, and being a troll is the desired result I'm going for.
A242: It only works for unarmed strikes, not natural attacks, but the Scorpion's Grasp feat from Sandstorm is Improved Grab, but for unarmed strikes.