Teuth, Rhubarb pie is delicious, and just another example of pie's versatility, and respect of function (taste) above form (awful, disgusting chemicals, stabilizers, leavening agents, colorants, fondant icing a.k.a. edible plastic).
And just to show you what an ignorant slut you are, you do not put the entire plant into the pie. Only the lovely, colorful, and delicious stalk. The leaf is actually deadly poison, making rhubarb pie more BAD-ASS. Its the pie version of Fugu.
So not only is pie tastier, more versatile, and purer than cake, it could also kick cake's ass in a cage match.