A prolific and precocious springtime "fruit," rhubarb looks like stalks of pinkish green or even magenta celery. Its flavor is much more tart, making it ideal company for sugar in sweet dishes like crisps, compotes, and pies (from which it gets its second name, "pie plant"). Rhubarb also lends a puckery-tart fruitiness to savory dishes and pairs very nicely with pork and poultry.
What Is Rhubarb?
Rhubarb is a member of the Rheum genus of plants. Though it's a hardy perennial vegetable, it's used more like a fruit. In fact, a New York customs court judge ruled in 1947 that is legally a fruit and the U.S. Department of Agriculture (USDA) officially classifies it as such. The plant is a popular addition to backyard gardens and easy to grow (even difficult to get rid of when you want to). It requires the cold weather to thrive and produces its familiar brilliantly colored stalks—ranging from red to pink to pale green—in the spring.
Only the stalks of the rhubarb plant are eaten because the large, triangular leaves are poisonous. They contain a higher concentration of oxalic acid than foods like spinach, broccoli, and cauliflower (which have perfectly safe levels). It's also thought that rhubarb leaves may contain a more potent unidentified toxin. While you'd likely have to eat a large amount of the leaves for it to be lethal, even small amounts can cause nausea and vomiting. To be safe, do not to eat or serve the leaves and keep them out of reach of children and pets.
How to Cook With Rhubarb
Rhubarb is easy to prepare. Due to their toxicity, trimming and discarding the leaves is essential. Wash the stalks well and trim off the dry ends as well. While it's tempting to peel the fibrous skin as you chop the stalks, try to resist this. The skin holds lots of color and flavor.
Two things happen to rhubarb when it's cooked: its juices thicken and it falls apart into fraying shreds of translucent fibers. Heavily cooked rhubarb has the perfect jellied consistency for rhubarb jam, as well as chutneys and compotes. It isn't so attractive when stir-fried or arranged on a tart. Quick heat yields tender but cohesive rhubarb pieces with rich flavor and a natural, glossy sheen.
What Does It Taste Like?
Raw rhubarb has a very tart taste and most people find it unpleasant. For this reason, it's almost always cooked with sugar because the sweetness counteracts the sour flavor.
Rhubarb's tart fruitiness makes it perfect to use in desserts and it's most often paired with strawberries. Its intense tartness makes it a nice foil for savory dishes, too. If you don't feel like cooking, try a simple snack and dip pieces of rhubarb in honey or sugar or boil it to make rhubarb juice.
Where to Buy Rhubarb
Hothouse rhubarb is available most of the year, while field-grown stalks are available in early spring, typically from April through June. The Pacific Northwest is lucky enough to have a second harvest of rhubarb between June and July. The short growing season means you should enjoy it when you see it. If you don't grow your own, it's often available at farmers markets and can be found in grocery stores.
Whatever their color, the stalks should be heavy and crisp with taut, shiny skin. Watch out for rubbery, fibrous, and dry stalks.
Store trimmed stalks in loose plastic in the crisper drawer of the fridge where it will keep for about a week. Many cooks prefer to wash it only before using it, but if you do it prior to storing, ensure the rhubarb has dried completely. To freeze, cut the rhubarb stalks into 1-inch chunks and seal in an airtight bag. Frozen rhubarb will keep up to a year at 0 F.
Nutrition and Benefits
Rhubarb stalks are highly nutritious, containing loads of calcium, manganese, vitamin C, vitamin K, fiber, and a whole host of antioxidants. It can also aid in digestion, relieve constipation, and might help soothe inflammation and lower cholesterol levels.
Rhubarb vs. Chard
At first glance, it can be easy to mistake rhubarb for some varieties of chard, specifically ruby red chard, which also has red stems and is often included in bundles of rainbow chard. The two are very different, however. First of all, chard is a member of the beet family, though it's not used as a root vegetable.
The stalks of both plants are edible, though only chard's leaves can be eaten. If you can compare the two side-by-side, you will notice that chard's leaves have more prominent veins and that the color extends all the way through. Rhubarb's veins tend to blend in with the leaf, though this depends on the variety. Taste is the biggest difference: where rhubarb is profoundly tart, chard tastes more like spinach.
Many varieties of rhubarb exist, including some with green stalks that are surprisingly sweet. There are two basic types of rhubarb found in markets and larger grocery stores: the older, traditional variety, with thicker, greener stalks, and the more intensely-colored, slender-stalked variety, sometimes called hothouse rhubarb. The deep red stalks certainly make for brighter, more attractive dishes, but the concentrated color indicates stronger tartness. The greener stalks have a nicely balanced, mellow flavor.