The other use for rhubarb leaves( or dilute Oxalic Acid) is...Ta da..the Musical link!!!
If you have a piece of wood with a fairly indifferent grain, or a not very visible grain pattern rub it with crushed fresh rhubarb leaves( or oxalic Acid solution about 2%) and it will enhanced the figuring!!!! the effect is very long lasting as the Oxalic reacts with some of the Tannins in the wood.