Rhubarb: it’s a leafy vegetable that makes such delicious pie that early Americans called it “the pie plant.” It’s a beautiful perennial in the garden: forming a four- or five-foot mound of ruffled leaves with glimpses of ruby red stalks underneath. In spring, huge stalks of flowers shoot forth; both in bud and flower, they look like some weirdly beautiful image a biologist might see under a microscope. I have an arrangement of them on our fireplace mantle.

The stalks are what make that scrumptious pie; the leaves themselves are poisonous. The reason is that they contain high levels of oxalic acid. Small amounts of oxalic acid are found in most leafy dark greens, and dozens of other fruits and vegetables from asparagus to watercress, including sweet corn and strawberries. Fortunately for us, the pale green to ruby red rhubarb stalks are completely and deliciously edible.

Until fairly recently (at least in America) rhubarb was found only in desserts; and mostly in pie form, alone or with strawberries, with which it naturally pairs. These days, it’s