Many consider rhubarb a fruit due to the dominance of desserts with rhubarb. However, rhubarb is botanically a vegetable. More surprisingly, rhubarb's primary role throughout history has been medicinal rather than culinary. Indeed, widespread culinary uses began only two centuries ago. In contrast, medicinal uses go back at least 5000 years to when Chinese used the dried roots as a laxative. The first documented uses in western civilization are 2100 years ago, when rhubarb roots were an ingredient in numerous medicinal remedies of the ancient Greeks and Romans. Dried rhubarb roots are also astringent. The astringent effects closely follow the cathartic impact, which made rhubarb roots a popular laxative in days of old. Dried rhubarb root is still sold as a laxative. It is therefore important to note that the medical efficacy of rhubarb roots varies significantly by variety. The original Chinese variety remaining the most efficacious while some varieties have no laxative value whatsoever.
There is no record of culinary uses of rhubarb prior to the 1800s. Widespread consumption of rhubarb stalks first began in Britain in the early 19
th century with its popular adoption as an ingredient in
desserts and wine making. Since that time rhubarb’s popularity has been highly variable, peaking before World War II in what Foust
1 called “rhubarb mania.” It was always more popular in Britain and the U.S. than elsewhere but rhubarb also achieved noteworthy popularity in Australia and New Zealand. Culinary uses also spread to northern Europe. At its most popular commercial quantities of rhubarb were grown outdoors as well as in greenhouses and dark cellars. Culinary use droped dramatically during WWII as a direct result of the depravations of war, most notably the rationing of sugar.
Rhubarb leaves are toxic and have no safe use for humanity. This is due to high concentrations of oxalic acid, an organic poison and corrosive found in many plants but present in relatively large amounts in rhubarb leaves. Other toxins may also exist
but based on oxalic acid alone 5 kilograms of the leaves provide a lethal dose to a human
2. (Although this varies by variety and even the phase of growth.) Still, all are well advised not to consume the leaves in any quantity whatsoever.
The word
rhubarb originates from Latin. The ancient Romans imported rhubarb roots from unknown, barbarian lands. The lands were beyond the Vogue river, sometimes known as the Rha river.
Rha was adopted to mean rhubarb. Imported from barbarians across the Rha the plant became
Rha barbarum and eventually
rhabarbarum, Latin for rhubarb. The modern word
rhubarb derives from
rhabarbarum.
Since WWII rhubarb production has rebounded but to only a fraction of pre-war levels. Today’s U.S. rhubarb production is almost exclusively outdoors with little if any commercial forcing. There are about 1300 acres devoted to rhubarb production, 60% in Washington state with Oregon and California next, and 1/2 acre in Black Forest, Colorado. Rhubarb production also resumed in England after the war but, as in the U.S., not at earlier "mania" levels.
Forcing, however, is still popular in England with Yorkshire the English leader in rhubarb production.
Formal research has concentrated in two laboratories: Stockbridge House Experimental Horticultural Station at Cawood, Selby, North Yorkshire, England, and; Clarksville Horticultural Experiment Station in Michigan. The focus was on commercial rhubarb production, including the development of plants suitable for mechanized harvest and the discovery of optimal techniques for forcing. It has proven very difficult to acquire records of those activities.
The Romans imported their roots from China, a fact unknown to them and first discovered many centuries after the demise of their empire. Mysterious origins notwithstanding, rhubarb’s usefulness as a cathartic was widely valued in Europe for millennia. Unlike some laxatives rhubarb roots are not only effective but also short lived and painless. Important, too, is the fact that cathartics played a more prominent role in medicine in ancient times than they do today. These factors helped motivate a variety of rhubarb-related activities in post-Renaissance Europe, including exploration to discover the Asian source, and allopatric transplanting and experimentation with the roots and plants. Although China was eventually discovered to be the source of the original and highest quality plants other varieties were discovered elsewhere in Asia. Many were imported and grown in Europe and Britain.
By the 13th century a handful of varieties had been imported to Britain and Europe. Experimentation and exploitation continued to focus on medical applications until the 19th century when culinary growing and experimentation quickly resulted in a few species hybridizing to over 60 species. Indeed, the plant is so plastic that knowing the true lineage of modern varieties is problematic. In many cases it must be sufficient to identify rhubarb species by their demonstrated characteristics rather than relying on a pedigree. This may seem imprecise but it is still useful. The plants are normally propagated through the roots and thereby breed true. Propagation by seeds, however, has always produced unpredictable results. While seed propagation is a viable mechanism for hybrid experimentation it is not yet effective for large-scale proliferation of extant, desirable characteristics. This is hardly unique to rhubarb. Indeed, when dealing with hybrid seeds it is often important to get the F1 seeds (first generation) as hybrids often don't propagate true through the seeds
3 of subsequent generations. This is why gardeners witness second generation plants, sprouting from seeds grown by last year's first generation hybrids, to exhibit significantly different characteristics than the parents.
The Renaissance and the Industrial Age brought attempts to discover the constituent elements of rhubarb responsible for the cathartic and astringent effects. Also, there were attempts to develop tests and procedures to ensure quality. These were rather unsuccessful until modern times. The nature of rhubarb's medicinal values were eventually understood, just in time for hybrid mayhem to cloud the issues. Anthraquinones, particularly emodin and rhein, now explain the laxative effects of rhubarb. The chemicals are known to exist in both the roots and the stalks, though the actual concentration varies from species to species and even annual
phases of growth.
As mentioned, rhubarb did not enjoy widespread consumption until the 19th century. Indeed, the modern market for culinary rhubarb was created virtually from scratch in 18241 by Joseph Myatt, a South London nurseryman with some rhubarb plants, a recipe for tarts, and enough gumption to convince others that the otherwise bitter plant could taste good when combined with something sweet. (Guess what crop Mr. Myatt was best know for producing ... strawberries.) The timing was perfect. Sugar was just becoming available and affordable and the rhubarb stalks were otherwise going to waste. There was nothing to lose! Adding to rhubarb’s popularity was the fact that it is generally ready for harvest well before most other vegetables. With forcing it can be made available even earlier. It was a welcome, fresh food after a long winter of preserves and meat. With such an explosion in popularity there were many other preservation techniques developed for rhubarb. These included drying, canning and, most recently, freezing.
Rhubarb species can be grouped into two broad categories, all horticulturally classified as members of the genus
Rheum. In one category, sometimes collectively called Victoria, the stalk exteriors vary in color from pure green to light red while the interior is green. The varieties in this category tend to be larger, more robust and relatively disease resistant. The second category consists of pure red rhubarb. These stalks are deep red inside and out. They tend to be smaller, less robust and more prone to diseases. In general the yield per plant per year of red rhubarb is about half that of Victoria plants. The Victoria group is by far the more common type of rhubarb in the U.S. Over 60 species of rhubarb are now known, mostly hybrids of the few species imported from Asia after the Renaissance. Rhubarb also grows wild in Alaska and may be native to that region. Varieties vary in appearance, taste, medicinal merit, yields, and date of harvest. There is no known variance in food value among varieties although the pure red is aesthetically preferred for some uses.
We rhubarb cultivators work to improve and understand our varieties. At High Altitude Rhubarb we are searching for a hybrid of red and green that will offer the color of the red and the robustness and size of the green. In the meantime, enjoy your rhubarb. It’s
good for you!
(high in calcium, vitamin C and fiber)