Rhubarb: The Toxic Yet Edible Veggie You Can Enjoy

Is it a fruit? A vegetable? People are often unsure, but one thing they do know for certain is that nothing tastes quite like it. While you might think we’re talking about a tomato, we’re actually referring to a different red plant: rhubarb.

What Is Rhubarb?

Rhubarb is a plant recognized for its frilly green leaves (we'll discuss those later) and its tart, vividly red stalks, which bear a striking resemblance to celery in both shape and texture. Originally from Asia, rhubarb is now cultivated across Europe and North America, with the most notable growing region being the Rhubarb Triangle, located between Wakefield, Morley, and Rothwell in the U.K.

In the U.S., the Pacific Northwest stands out as a prime region for rhubarb cultivation, as the plant flourishes in that environment. Tim Richter, a fourth-generation rhubarb farmer from Puyallup, Washington, operates the EG Richter Family Farm.

Richter's great-grandfather left Minnesota for the West during the Gold Rush, but missed out on that fortune and instead began a family farm in the late 1800s, growing rhubarb and other crops. This farm has remained in the family, and Richter’s son now plays a role in its operation.

"There’s no better place in the world to grow rhubarb than the Puyallup valley. They prefer a moist, mild climate, and that’s exactly what we have in western Washington," says Richter. "When rhubarb gets too much sun and heat, it still grows, but it loses its color. The stalks turn a much greener shade."

Field Rhubarb vs. Hothouse Rhubarb

Rhubarb doesn't all taste or appear the same. Two main varieties of rhubarb are available in the market: field rhubarb and forced (also known as hothouse) rhubarb.

As the name suggests, field rhubarb is harvested directly from the field. When exposed to natural outdoor light, field rhubarb can develop a greener tint and a slightly stringy texture when you break open the stalk, according to Richter.

Hothouse rhubarb, on the other hand, undergoes a more controlled, precise cultivation process. It is grown in a hothouse where light is intentionally kept from the plant to bring out its natural red color. The only time the rhubarb sees indoor lighting is during the harvesting process. Richter explains the meticulous effort behind hothouse rhubarb cultivation:

Richter notes that due to the lack of light exposure, the hothouse rhubarb's leaves often turn "bright yellow" while its stalks become a "brilliant red". This rare coloration and the detailed growing method make hothouse rhubarb more expensive than field-grown varieties.

As for which variety tastes better? Richter remains neutral on that matter.

"If you place two stalks side by side, one hothouse and one field, you’ll likely notice the difference. I wouldn't say one is better than the other. They're simply different."

Outside the U.S., Yorkshire farmers in the U.K. are internationally recognized for their hothouse, or forced, rhubarb. They're particularly famous for the age-old practice of harvesting rhubarb by candlelight, which helps keep the stalks tender.

The Rise and Fall of Rhubarb

The popularity of rhubarb grown in the U.S. has diminished in recent years, following its peak during the 1960s and 1970s, according to Richter. With a flood of international produce entering the market, it’s become difficult for the robust red plant to compete. Additionally, since most recipes call for cooking rhubarb, it’s often less appealing than fresh, ready-to-eat produce.

"Back when my great-grandfather and grandfather were doing it, there wasn’t all this imported produce from South America and other parts of the world. Rhubarb was one of the first big crops on the market. It was a major deal," says Richter.

Richter mentions that as consumer demand has dropped, American farmers are growing less rhubarb, adjusting their supply to match the decline.

However, rhubarb still has a dedicated following, as evidenced by the numerous rhubarb-focused festivals held in places like Wakefield in the U.K., Pennsylvania Dutch Country, and Lanesboro (known as the Rhubarb Capital of Minnesota).

If you're looking to buy rhubarb, Richter mentions that it’s readily available at many major chain grocery stores in the U.S., including Kroger and Safeway.

So, Is Rhubarb a Fruit or a Vegetable?

Given its common use in sweet dishes, it’s understandable why home cooks might assume that rhubarb is a fruit. In fact, in 1947, a U.S. Customs court in Buffalo, New York, ruled rhubarb to be a fruit because it was mostly used in that way in cooking. This classification allowed rhubarb to be taxed at a lower rate when imported, even though rhubarb is technically not a fruit.

Surprised? Yes, despite its legal classification, rhubarb is botanically a vegetable. The rhubarb stalk, known as a petiole, is the edible part that connects a leaf to the stem. This makes rhubarb a vegetable in botanical terms.

However, if you prefer to continue calling it a fruit, Richter won’t hold it against you. "For the person cooking it, I would say rhubarb is a fruit."

Is Rhubarb Poisonous?

Generally, only the stalk of the rhubarb plant is consumed, and it’s safe to eat either raw or cooked, as stated by Richter. The stalk doesn’t contain any harmful toxins, and eating it usually doesn’t cause any illness. However, you’ll likely want to sweeten or cook the stalk to improve its flavor.

Rhubarb leaves, however, are an entirely different matter and should absolutely be avoided. These leaves contain a deadly toxin called oxalic acid, which is far more concentrated in rhubarb leaves than in most other plants that also have small amounts of this compound, making them dangerously toxic to humans.

Although consuming a large amount of rhubarb leaves is unlikely to lead to a fatal dose of oxalic acid in one go, the danger remains. Even ingesting smaller amounts can cause symptoms like nausea and vomiting.

To stay safe, avoid eating the rhubarb leaves. On the bright side, the rhubarb stalks are perfectly fine to consume.

How Do You Cook Rhubarb?

Rhubarb offers a wide array of cooking options. The classic choice is, of course, pie. So synonymous is rhubarb with pie-making that it has earned the nickname 'the pie plant,' as Richter points out. Any respectable rhubarb cookbook will likely feature the beloved strawberry rhubarb pie, which blends the sweetness of strawberries with the tangy kick of rhubarb. Apples also pair wonderfully with rhubarb in many recipes.

If you're in the mood for something a bit more inventive, Richter recommends trying a rhubarb crisp, similar to a traditional apple crisp. One of Richter's personal favorites involves simmering rhubarb in a pan, sweetening it with sugar, and then letting it cool before serving it on top of a scoop of vanilla ice cream.

For more sweet rhubarb treats, you can try making rhubarb cobbler, rhubarb bread, rhubarb cake, or rhubarb cookies. If you're in the mood for savory dishes, options include baked Brie with rhubarb chutney, rhubarb chicken, rhubarb fish, and rhubarb soup. For the more adventurous, you can even make a delicious rhubarb mead.

But if you're not feeling up to cooking, simply grab a raw rhubarb stalk, dip it in sugar, and enjoy a crunchy snack. Richter fondly recalls enjoying this as a treat during his childhood.

Health Benefits of Rhubarb

While the debate on whether rhubarb is a fruit or a vegetable rages on, the ancient Chinese recognized rhubarb as a potent purgative. In fact, Marco Polo is said to have encountered rhubarb during his travels to China in 1271. The Romans, too, valued rhubarb for its cleansing properties, often using it as a medicine for digestive issues.

Rhubarb was introduced to Europe through trade, where it quickly became prized as a medicinal plant, particularly in Britain. In 1771, Benjamin Franklin presented Chinese rhubarb to his friend John Bartram, a botanist in the American colonies, who worked under the British crown. However, it wasn’t until the early 19th century that rhubarb’s reputation shifted, moving from medicinal uses to a key ingredient in desserts like pies in both North America and the United Kingdom.

Rhubarb's health benefits have long been acknowledged in America. According to Richter, it is traditionally believed to support digestion, though scientific evidence on its effectiveness remains inconclusive.

In modern times, researchers are exploring rhubarb for its potential therapeutic effects. These include applications in treating heatstroke, kidney failure, wound healing, and cancer, as well as its anti-inflammatory and antioxidant properties.