Tis the season for rhubarb, the pie-friendly, perennial favorite of springtime vegetables. Or is it a fruit? Like the bamboozling tomato, rhubarb challenges easy classification as vegetable or fruit. Most experts agree that rhubarb is, indeed, a vegetable, since the edible part of the plant falls under the grouping of root, stem or leaf. Conversely, plants whose edible bits are, to put it graphically, the matured ovary of a flower, take the label fruit. Unfortunately, even this wordy explanation fails to hold up in every case. Anomalies of the produce aisle like rhubarb and tomatoes illustrate how the classification of plants as vegetable or fruit is largely determined by custom, culture, and culinary practice. Rhubarb most often appears in sweet desserts alongside other fruit (such as with strawberries, a duo as classic as bread and butter), and so some cookbooks may index their rhubarb recipes among other fruit dishes.
history of cultivation & nutritional facts
The Ancient Chinese are credited with first cultivating rhubarb some several thousand years ago. Record of the plant and its medicinal properties appear in The Divine Farmer’s Herb-Root Classic, a catalog of hundreds of medicinal plant species that laid the foundation for herbalogical studies in China for thousands of years to come. (Legendary Chinese emperor Shen Nong, who lived and worked a couple millennia before the catalog’s publication, is believed to have inspired not only The Divine Farmer, but is perhaps one of the primary reasons for China’s past and present preeminence in the field of medicine.)
However, it was Russian rhubarb, and not the Chinese variety, which first captured the attention of Europeans in the Middle Ages. For centuries, rhubarb has grown wild along Russia’s River Volga, yet thanks to its medicinal properties, this highly sought after plant was sold at exorbitant prices in Europe (think ten times the price of cinnamon and twice the price of opium!). You can imagine explorer Marco Polo’s pleasure upon discovering the Chinese variety of rhubarb, which could be transported from Asia and sold for a pretty profit in Europe. The plant was marketed primarily for its balancing effect on the digestive system, but we now know it’s a rich source of potassium, vitamin C and fiber, as well.
What do ginger, quaking aspen and rhubarb plants have in common? All grow from rhizomes, or “creeping rootstalks.” Rhizomes are stems that grow horizontally underground and send out new shoots from its nodes. The long, fleshy stalk of rhubarb plants–the part that shows up in your pie–are called petioles. Whatever you do, don’t eat the leaves. Rhubarb leaves are considered toxic to humans due to a high level of oxalic acid. But don’t worry: the percentage of oxalic acid in the petioles is much lower, so rhubarb stalks can safely be eaten raw (though you might find raw rhubarb’s sourness rather unpalatable.)
According to the Oxford English Dictionary, rhubarb is baseball slang for a heated dispute. Intriguingly, no explanation is given.