Tea's Scientific Name---The Basics
Tea's Scientific Name—The Basics
It's not uncommon for the common names of plants to vary from place to place and time period to time period.  This also holds true for tea plants (see Common Names:  What's in a Name? ).  A scientific name, on the other hand, is the same around the world.  So while North Americans call it tea and Russians call it chai, it Camellia sinensis in both places and everywhere in between.
Scientific names are important because they provide the means for growers and those in the scientific community to accurately reference and discuss the same plant.  Even if you're not a scientist, the one way to ensure you're getting the exact plant you want at your local nursery is to use its scientific name. 
Yes, scientific names are Latin.  Yes, they're standardized.  But don't let either of those things intimidate you.   If you know a few basics, they're also fun as you can start to puzzle out details of the plants they're naming.  Don't forget that English is full of words with Latin origins, so it's often logical to work out meanings.  The following is a very brief overview of scientific names as they relate to tea.  
Early Scientific Names for Tea
The first scientific mention of tea in the West came in 1712 when it was called Thea.  Thea came from t'e, the word used for tea in the Amoy dialect.  Then in 1753 Carl von Linné of Sweden (more commonly known as Linnaeus) included tea in his groundbreaking work, Species Plantarum.  Although he described tea plants in its pages, the work is best known for the simple and effective formula for naming plants that Linnaeus introduced in it to replace an extraordinarily cumbersome system.  In fact, the system he introduced is the one we still use today.
With his binomial (two names) system, every plant is assigned two latinized names that together uniquely identify it: a genus and a specific epithet that together comprise the species name.  For tea, Camellia is the plant's genus name, sinensis is its specific epithet, and the species is Camellia sinensis.  Explanations follow.
Genus, Camellia
Plants of the same genus are closely related based on similarities in their flowers, fruits, and sometimes other plant parts or traits.  While there are approximately 80 species of plants in the genus Camellia, they are all small evergreens native to eastern Asia having simple leaves with serrated edges (see Tea Plants—What They Look Like ). 
A genus is often named after a person (a latinized version of it) or after ancient Greek and Roman names given to plants.  Camellia is most likely named for Georg Josef Kamel.  He was a Jesuit missionary and pharmacist who collected plants while traveling through Asia.  He is known to have sent plants from the Philippines to Europe between 1683–1700, and later he wrote about them using his latinized name of  Camĕllus.  Thus, tea's genus became Camellia. 
Specific Epithet, sinensis
A specific epithet further defines a plant to distinguish it from related plants of the same genus.  In the case of tea, the word sinensis indicates the plant's origin in China.  It stems from the Greek and Roman names for China, "Sinai" or "Sinae."
Probably the most common other Camellia is the garden camellia, Camellia japonica (native to Japan, but successfully grown in mild parts of the U.S. like the Pacific Northwest and the Carolinas).  It's known for its gorgeous blossoms that can reach 5" (13 cm.) in diameter.   Flower size is one of the characteristics distinguishing it from the tea plant whose blooms are much smaller.
Species, Camellia sinensis
Plants within a species are similar in form, share other distinctive traits, and are capable of interbreeding.  A species is usually isolated reproductively from other related species.
By way of example, eastern white pine (Pinus strobus) and ponderosa pine (Pinus ponderosa) are different but related species.  While they share characteristics common to all pines, each has its own distinctive traits as well.  Their natural distributions also vary, with Pinus strobus native to the eastern U.S. and Pinus ponderosa to the western states.  Different geographic ranges allowed each species to evolve independently over time and made cross-pollination between them impossible.  (When we speak of a plant's natural distribution or nativity, it means the geographic range where a plant grew prior to the time humans intervened to spread populations.) 
Bringing the discussion back to tea...in addition to the characteristics listed for the genus Camellia, all Camellia sinensis have other similarities including white flowers about 1" (2.5 cm.) in diameter, multiple stamens, and yellow anthers.  They cross-pollinate easily, and this has resulted in a wide range of natural variability within the species.  Geographically, the tea plant is native to China while the garden camellia (Camellia japonica) is native to Japan and Korea.
Even More Distinction—Variety
In Tea Plants—What They Look Like we describe the two primary kinds of tea plants—Camellia sinensis var. sinensis and Camellia sinensis var. assamica.  The "var." part of the scientific name refers to variety and is a further refinement of the species.  Plants are differentiated into varieties when there are populations within a species that have characteristics distinct from other populations of that same species, and these traits are passed on from generation to generation.  Varieties generally have their own geographic range.
As well as having other defining characteristics, Camellia sinensis var. sinensis is consistently hardier, has smaller leaves, and is more shrublike in habit than Camellia sinensis var. assamica.  (See Tea Plants—What They Look Like for more details.)  You already know from its species name that "var. sinensis" refers to the plant's origin in China; the larger leafed variety (var. assamica) originated in the Assam region of India.
The Evolution of Tea's Name
Tea's scientific name has been changed multiple times since its first use. 
In Volume 1 of Species Plantarum Linnaeus referred to tea as Thea sinensis; in Volume 2 he called it Camellia sinensis.  A later edition less than a decade later (when it was thought that black and green tea came from different plants) named black tea Thea bohea and green tea Thea viridis.  Thus, the tea plant's scientific name has bounced around between Thea and Camellia over the years.  In 1949 tea was categorized as Thea sinensis, with four different variants recognized.  By 1961 this was narrowed to two varieties.  Eventually the plant came to be categorized as the species Camellia sinensis.
Lest you think the scientific name changes were simply the result of widespread indecisiveness among botanists, imagine yourself in the eighteenth century.  The task of botanists at the time was to piece together an inventory of the world's flora, most of which they knew nothing about—actually, they had never even seen these plants before explorers returned with specimens from their overseas voyages.  Classification during this time was accomplished without telephones, e-mail, the Internet, a solid body of research, or most of the other conveniences we take for granted today.