Barry Swanson, professor of food science, and I see eye to eye on at least one significant issue. We like our rhubarb pie to be made exclusively with rhubarb. NOT strawberries. Just rhubarb.

However, Swanson actually prefers his rhubarb as sauce, over ice cream. Although Swanson does no research on the tart vegetable, he is an avid enthusiast and considers it an acidic parallel to his work with cranberries. And obviously, given his rhubarb enthusiasm, Swanson is from the Midwest, where every old farmstead has a rhubarb patch. “Mom always made rhubarb pie in the spring,” he says.

Rhubarb is also known by Midwesterners as a spring tonic, a purgative. In other words, a laxative, says Swanson.

In fact, the use of rhubarb as food is relatively recent. But it goes way back as a medicinal, particularly in China. Rhubarb was first mentioned, as a purgative and stomachic, in the Chinese herbal Pen-King, which is believed to date from 2700 B.C.

Medicinal use, however, was generally limited to the roots. Rhubarb found its way to Europe by way of Turkey and Russia. It was first planted in England in 1777 by an apothecary named Hayward. Someone obviously decided to try the stems, found they were great with substantial amounts of sugar, and rhubarb thus joined our culinary heritage.

Many of the 60 accessions of rhubarb maintained by the Western Regional Plant Introduction Station here at Washington State University are medicinal, says collection curator Barbara Hellier (’00 M.S.). The WRPIS is one of four plant introduction stations in the USDA-ARS National Plant Germplasm System, which is responsible for collecting and maintaining seed and clonal germplasm. The station here actually maintains the backup collection, the main collection being in Palmer, Alaska.

Hellier says those 60 accessions represent a pretty good selection of the world’s rhubarb cultivars, though the selection of species within the genus could benefit from further collecting.

Washington is the largest producer of rhubarb in the nation, with most of it grown around Sumner. When I spoke with him in late February, Tim Laughlin, the sales manager for the Washington Rhubarb Growers Association, said the growers were sending out 1,500 15-pound cases of hothouse rhubarb a week. Outside field season runs from March to September, resulting in about 65,000 20-pound boxes. Although some Washington rhubarb is sent frozen to Japan, most is sold domestically, fresh for household consumption and frozen for restaurants.

Although the climate of Sumner is apparently ideal for rhubarb, the variety grown there, Red Crimson, adds greatly to the crop’s quality. Laughlin said a Michigan grower recently tried to buy some, but the cooperative’s farmers wouldn’t sell any for less than $200 a bulb.

With a pH of around 3.1, rhubarb is not quite as tart as one might think from chewing on a raw stalk (a lemon is about 2.0). It just doesn’t have any sugar to balance out the acidity. Try substituting it for other acidic ingredients. (I’m working on a rhubarb-chipotle barbecue sauce.) However, as Swanson insists, rhubarb is best at its simplest. Just chop some up and heat with a little water and sugar to taste, which will be quite a bit. Pour the sauce over your favorite ice cream.

If you Google the WSU Web site for rhubarb, you’ll turn up lots of good rhubarb recipes, generally in spring editions of Extension newsletters.

By the way, don’t eat the leaves. With high levels of oxalates and, probably, anthraquinone glycosides, they are toxic. Swanson says you’d have to eat a lot to do any harm. But why bother, when you’ve got the stalks?