When thinking of tea, it’s easy to picture dozens of varieties, packed in colorful boxes, readily available on a local grocery store’s shelves. But this is just a small glimpse of the current tea industry. Tea is second only to water in terms of global consumption, and there are an astonishing 350 to 500 varieties, all thanks to a single plant species: Camellia sinensis. This enormous variety is due to millennia of cultivating C. sinensis, studying how different climates and soils affect its growth, and investigating different ways to prepare its leaves for consumption.
Camellia sinensis: The plant that tea comes from, Camellia sinensis, is a small evergreen that probably originated in southwestern China (specifically on the Yunnan and Guizhou plateaus, though this is hotly contested). It’s been living there for a very long time, dating back to the Tertiary period (65 million to 2.6 million years ago), and luckily survived the great ice ages because the glaciers didn’t reach these plateaus. C. sinensis continued to spread throughout southeastern Asia, thriving in certain mountainous areas.
The plants have small, rose-like white flowers and can grow into towering trees, often up to 40 feet tall, with records of 108-foot-tall living behemoths that may be more than 1,700 years old. However, to keep it at a feasible height for picking leaves for tea, C. sinensis is carefully pruned down to a two- or three-foot-tall bush. Two main varieties are generally recognized, the “China bush” (Camellia sinensis var. sinensis) and the “Assam bush” (var. assamica). These varieties look rather different from each other physically (the China bush grows more like a bush and the Assam bush more like a tree) and prefer different conditions for ideal growth (the China bush prospers on cool mountainsides and the Assam bush prefers jungle-like areas), but the differences in their genetics are mostly negligible.
The Creation of Tea: It will probably never be known for certain who first made a drink from leaves of the tea plant, but legends exist and some educated guesses for how it most likely came about have been made. Some hypothesize that prehistoric people may have found wild tea trees and, looking for food to eat, could have chewed on the leaves and found that this gave them more energy to carry out their daily routines. Perhaps they even started to tend some of these plants. What are thought to be ancient tea gardens have been discovered (specifically growing in the depths of the Brahmaputra valley), but it’s hard to know how old such gardens are.
Some Chinese legends credit tea’s accidental discovery to Shennong (known as “the Divine Cultivator” because he’s also credited with inventing agriculture). As the legend goes, sometime around 3000 BCE, Shennong was boiling water outside and leaves from the tea plant fell into his water, creating a drink he enjoyed and thought to have medicinal properties.
During the Shang dynasty (1766 to 1050 BCE), fresh tea leaves were boiled in water with other plant materials including leaves, barks, and seeds to create medicinal brews used to treat a variety of ailments. By about 300 BCE, tea was prepared for the first time without other plant material and consumed not necessarily as a medicinal tonic, but as an invigorating, bitter drink. Drinking tea quickly became popular among monks and priests of Buddhism, Taoism, and Confucianism, as they found it helped them stay awake while meditating for long periods of time. They were enthusiastic supporters, proclaiming that all people should drink tea. As more and more people drank it on a daily basis, leaves were often dried and processed to make tea, as it was becoming unfeasible to meet increased demands using fresh leaves.
The event that helped spread tea-drinking’s popularity throughout China more than anything else during these early days may have been the building of the Great Wall. As workers were brought from across China to create the wall under Emperor Qin Shihuangdi (221 to 210 BCE), information quickly spread about relatively localized customs, such as tea drinking, which was previously popular mostly in the western provinces. Soon, tea-drinking was trendy throughout the country. It was around 50 BCE that tea plants began being cultivated for the first time to supply the desired leaves.
An Evolving Drink: Over the next several centuries, tea went through many metamorphoses as prevailing tastes changed and challenges arose. The first major transformation, which took place between 200 and 600 CE, changed tea from a bitter and rather crude drink to a sweeter beverage — though not sweet by today’s standards! Until this point, tea leaves were dried and then charred before boiling to make tea; but people found that if they instead steamed the leaves, the pliant product could be compressed into little tea cakes which they then baked. The baked cakes kept well, and small bits could be chipped off and boiled in water for tea. These tea “bricks” became a common form of currency, and were so essential to people living outside of China that they traded horses for them.
But more importantly, these cakes made tea that was much less bitter than tea produced by the dried, charred leaves. This made tea-drinking a pleasurable activity, which was elaborately refined during the Tang dynasty (618 to 907 CE). Also during this time, tea-drinking and other customs then current in China made their way to Japan for the first time, where they took on a life of their own. However, tea was not enjoyed beyond the Japanese emperor and his court until centuries later, around 1200 CE, when Zen priests planted many tea plants in Japan.
During the Song dynasty (960 to 1279 CE), steamed tea leaves were more finely ground to create cakes made of powdered tea. This further refinement changed how tea was commonly served; now the powder could be scraped straight into the drinking bowl and whipped with boiling water to create a beautiful green froth. At this time teahouses became popular, providing places to not only share tea and snacks in public, but to socialize, gossip, play games, carry out business, and more.
But still tea kept on changing; by the end of the Song dynasty, people were experimenting with making tea from loose leaves, which made it easier to measure out. When Kublai Khan and the Mongol Empire took over China (1271 to 1368 CE), they further explored the new loose-leaf technology. However, many still preferred their tea powdered because of its supposed superior flavor.
After the Mongols, the Ming dynasty (1368 to 1644 CE) developed two new major types of tea: black tea and scented teas. The tea brewed up until this time was primarily what we’d know today as green tea, but during the Ming dynasty it was found that black tea could be made by oxidizing the leaves. Although the Chinese preferred green tea over black tea, black tea made better tea bricks; they could withstand travel over long distances without getting ruined from extreme temperatures or mold. This made black tea ideal for exportation. Using flower petals, such as from jasmine and rose, to make perfumed teas also became popular at this time.
Tea Goes to Europe: During this experimental time, tea made its way from China to Europe through Dutch traders around 1610 CE. It’s thought that Europeans added milk to their tea because they wanted to imitate how they heard the emperor of China drank his tea. However, the emperor of the time was a Manchu tribesman of the Qing dynasty (1644 to 1911 CE), and the tribesmen preferred black tea with fermented mare’s milk added to it. (This is also how the Mongols drank their tea.) Of course, the rest of China still preferred green tea without milk, but perhaps the Europeans were only interested in the Emperor’s habits. In addition to cream, the British also added sugar, another new import, making their twice-daily tea drinking routine quite the reenergizing experience.
Early 20th Century American Innovations: Two major tea “improvements” took place in the 1900s in the U.S: the tea bag and iced tea. In 1904, the World’s Fair in St. Louis was a real scorcher, and tea vendors with hot Indian black tea did not fare well. However, tea plantation owner Richard Blechynden had a great idea: Pour the tea over ice. Thus, iced tea was born, and it has become increasingly popular in the U.S., as today over 80 percent of tea consumed in the U.S. is iced (mostly black) tea.
The invention of the tea bag came about in a similarly unplanned manner. In 1908, Thomas Sullivan, a tea importer in New York, sent out tea samples in little silk bags. When people found they could make tea with the leaves still in the bag, demand rose for it, though many tea connoisseurs still think that tea bags make lower-quality tea.
Tea Today: Tea is now produced in more than 45 countries, spanning several continents; it’s hard to meet the demand for a beverage that’s second only to water! While there are now hundreds of different teas available for the interested consumer, and many groupings, the four main groups are green teas, black teas, white teas, and oolong teas.They differ mainly by where the plants are grown and how the leaves have been prepared. The tea leaves are picked (usually the top two leaves and a bud at a time) primarily during the spring, but they can be picked during the rest of the season depending on where they are grown and what kind of tea will be made.
To make green tea, the leaves are steamed, then rolled or dried. To make black tea the leaves are sometimes rolled or cut, and then allowed to undergo full oxidation (the leaves are left to turn brown) before drying. Some consider black tea to be an extension of making oolong tea, which also requires some bruising of the leaves, but then only a short oxidation step before drying. And green tea is similar to white tea in that they both skip the oxidation step, but leaves for white tea are not rolled. Often many different varieties are blended together to create the final store-bought product. For example, most black teas actually contain a few dozen different black tea varieties made in a couple different countries.
Herbal Teas: Herbal “teas” have also become very popular, though technically they’re not a “tea” but are an herbal “infusion” or “tisane” because they do not contain leaves of the Camellia sinensis plant. Herbal “teas” instead contain different herbs, leaves, dried fruits, flowers, and more. Although strictly herbal “teas” do not contain C. sinensis, boiling various plant matter with tea leaves to create rich brews is a long tradition. Around 200 to 600 CE, such concoctions frequently included onions, orange, and ginger. Later, during the Tang dynasty (618 to 907 CE) cloves and peppermint, and the occasional delicate flower or fruit for court ladies, were added to this mixture. Still later, the Song dynasty (960 to 1279 CE) experimented with adding different juices, including pickle juice and plum juice, the latter a particularly sweet treat. While many parts of Europe today enjoy cream in their tea, this was not how it was originally prepared in Europe, but spices such as nutmeg, ginger, saffron, and salt were added instead. For the avid tea drinker, perhaps these historical examples will give inspiration for the next experimental brew.
Tea and Your Health: Stay tuned for the next “Biology Bytes” in two weeks to read about what exactly is the biochemistry that takes place in a good cup of tea, how this varies from one type of tea to another, and the hotly debated controversy of what drinking tea can (and can’t) do for one’s health.
For more details on tea and its historical biology, see Mary Lou Heiss and Robert J. Heiss’ book The Story of Tea, Kit Chow and Ione Kramer’s book All the Tea in China, Bennett Alan Weinberg and Bonnie K. Bealer’s book The World of Caffeine, Yukihiko Hara’s book Green Tea: Health Benefits and Applications, or Wikipedia’s articles on Tea and Camellia sinensis.
Biology Bytes author Teisha Rowland is a science writer, blogger at All Things Stem Cell, and graduate student in molecular, cellular, and developmental biology at UCSB, where she studies stem cells. Send any ideas for future columns to her at firstname.lastname@example.org.