Before Linnaeus, a plantain's scientific name ran to a dozen Latin words
Early botanists tried to make a species name double as its description, and it got out of hand. One plantain was labelled Plantago foliis ovato-lanceolatus pubescentibus, spica cylindrica, scapo tereti, a full sentence about its leaves, spike and stalk. Today the same plant is simply Plantago media, thanks to a Swedish botanist's two-word shortcut.
Binomial nomenclature gives every species a two-part name in Latin form. The first word is the genus, and the second, the specific epithet, singles out the species within it, as in Homo sapiens. The genus is capitalised and the epithet is not, even when it honours a person, and both are set in italics. After first mention the genus shrinks to an initial, which is why a phlox named after the botanist Thomas Drummond can appear as P. drummondii.
The older polynomial approach asked names to do two jobs at once, labelling a species and diagnosing it. As more species were found, the descriptions grew unwieldy. Caspar Bauhin, who lived from 1560 to 1624, took an early step by trimming many Latin descriptions to two words. The Swedish botanist and physician Carl Linnaeus then made it systematic in his 1753 Species Plantarum, consistently pairing each genus with a one-word trivial name.
His key insight was that a name need not describe anything. It could simply be a unique tag, even one borrowed from a person. A spiderwort that an earlier herbal had described at length became Tradescantia virginiana, honouring the English gardener John Tradescant the Younger, and a parrot was named Psittacus alexandri after Alexander the Great, whose armies brought eastern parakeets to Greece.
The system works because it is short, international and stable. Each species can have only one correct name under the relevant code, usually the earliest one published, whereas common names change from language to language. When a species moves to another genus, the original author's name goes in parentheses, as with the house sparrow, which Linnaeus first called Fringilla domestica. Some binomials have escaped into everyday speech, including E. coli, Aloe vera and Tyrannosaurus rex.
Source: Binomial nomenclature
