which looks like a pink celery stalk, is botanically a vegetable, but
it is used as a fruit, largely in pies and sauces. The ancient Chinese
cultivated the plant for its roots, which reputedly have medicinal properties.
The roots and leaves aren't eaten; indeed, the leaves are highly poisonous.
At one time, the toxicity was attributed to their exceedingly high levels
of oxalic acid, a substance that can interfere with iron and calcium
absorption. However, the exact source of the leaf toxin has yet to be
determined, since rhubarb stalks also contain significant amounts of
oxalic acid (as do a few other foods, such as spinach).
Rhubarb stalks are extremely tart and they require sweetening to make
them appetising. This can increase their calorie content considerably.
Choose well coloured, good sized, straight, firm crisp stalks. Avoid
stalks that are limp. If the leaves are attached, they should look fresh
and crisp; small leaves usually indicate younger, more tender stalks.
If you buy rhubarb stalks with the leaves still attached, cut off the
leaves as soon as you get home. Never eat the leaves, raw or cooked:
They are poisonous. Place the stalks in plastic bags and store them
in the refrigerator crisper, where they will keep for about a week.