Rhubarb Upside Down Cake and Rhubarb 101~ Got a few extra minutes? Then you have enough time to make Rhubarb Upside Down Cake, it's fast, easy and delicious. Now let's talk rhubarb for a few minutes and get a short lesson in Rhubarb 101. Rhubarb [ROO-bahrb] Thick, celerylike stalks of this buckwheat family member can