Short answers, pulled from the story.
The name basil derives from the Latin basilius and the Greek basilikón phytón, meaning "royal" or "kingly plant." The royal label may reflect the belief that basil was used in the production of royal perfumes. In French it is known as l'herbe royale, the royal herb.
Basil is native to tropical regions stretching from Central Africa to Southeast Asia, with India at the heart of its original range. Human cultivation has since spread it globally, and it is now grown commercially in Mediterranean, temperate, and subtropical regions worldwide.
European basil's essential oil contains high concentrations of linalool and methyl chavicol (estragole) in a ratio of roughly 3 to 1. The clove-like scent of sweet basil comes from eugenol, which is synthesized in the plant from coniferyl acetate and NADPH. Lemon basil's citrus quality comes from a different compound, citral.
Ocimum basilicum has at least 60 varieties, which complicates its taxonomy. The cultivars range from Genovese and Thai basil to purple varieties such as Dark Opal and Purple Delight, as well as aromatic types including cinnamon basil and anise basil.
Downy mildew, caused by Peronospora belbahrii, was first reported in Italy in 2003, appeared in Florida in 2007, and by 2008 had spread along the eastern United States and into Canada. Basil cultivars resistant to P. belbahrii have since been developed.
Giovanni Boccaccio featured a pot of basil as a central object in the fifth story of the fourth day of his 14th-century Decameron. John Keats adapted the story into his 1814 poem "Isabella, or the Pot of Basil," which then inspired two Pre-Raphaelite paintings: John Everett Millais's Isabella in 1849 and William Holman Hunt's Isabella and the Pot of Basil in 1868.