Easily confused with : Black Horehound, Field Woundwort (apart from Field Woundworts' rarity),
Limestone Woundwort (which is even rarer), and other members of the
Dead-Nettle family. [The other members of the same Clinopodium Genus (the
Calamints) are quite dissimilar].
Identifying Features : the tiered whorls of mauve-coloured flowers with many empty sepal tubes on dis-continuous stems. Unlike many mints, the leaves are not sharply toothed, and have slightly rippled edges instead.
No relation to :
Garden Basil [Ocimum basilicum] which still belongs to the same family (Lamiaceae), but is in a different Genus (Ocimum). Garden Basil has white flowers as opposed to the mauve coloured flowers of Wild Basil, and it also smells much more strongly (of Basil, a herb used mostly in Italian cooking).
Wild Basil has the propensity to grow another whorl of flowers atop an already existing top-most whorl, rather like a candelabra. Of course, many (but not all) Dead-Nettle Family plants have chandelier-like whorls of flowers up a continuous and un-broken stem, but the chandeliers in Wild Basil are different: they are not on a part of the same stem, but on a new stem grown from somewhere near the middle of the existing topmost whorl. Jerusalem Sage and Turkish Sage also exhibit this behaviour. The separate tiered stems are often thinner than those below them; and the corresponding whorls not as large: much more like a (albeit upside-down) chandelier.
The essential oil obtained from Basil contains Linalool (15-50%) and Estragole (Methyl Chavicol) as the two main constituents, with varying smaller amounts of Camphor, Eugenol, Limonene and
Citronellol is a monoterpenoid which occurs in two distinct enantiomers or stereo-isomers, (+)-Citronellol (in citronella oils, and the (-)-Citronella isomer which is the more common and occurs in rose oils and
Pelargonium. It is used in perfumes, but should be avoided by those allergic to perfumes such as your author. Both smell of
rose petals in slightly differing ways.