Plant 267

Salvia officinalis L. (Lamiaceae)

Common sage

'Why should a man die whilst sage grows in his garden?' This restating of a familiar medieval proverb refers to a widespread believe, still prevalent today, that common sage is a panacea. The Roman author Pliny used the name salvia, itself derived from the Latin meaning 'safe' or 'whole', to refer to sage. Carolus Linnaeus took this classical name for the whole sage genus, which comprises over 900 species distributed across the tropical and temperate regions of the world. The genus is especially species rich in Central and South America, and western and eastern Asia.

Traditionally, Salvia is separated from other members of the Lamiaceae, such as thyme, mint and basil, by its two stamens that are arranged as an elaborate lever device, which is part of the insect-pollination mechanism. Detailed analyses of Salvia species relationships have shown that similar staminal levers evolved on at least three separate occasions in the genus, but in subtly different ways.

Salvia officinalis is a small, evergreen shrub with greyish, downy, spear-shaped, aromatic leaves and spikes of purplish, sometimes white, flowers. All parts of the plant are covered in glandular hairs. There are five distinct types of glandular hairs (one mushroom-like and four shaped like lollipops) that differ in their structure and chemical secretions, in addition to other hair types.

Common sage is naturally distributed along the northern coast of the Mediterranean. As an ancient introduction to many parts of the temperate world, it has found favour in medicine, cookery and horticulture. Evidence for the medicinal value of sage is contradictory at best but, in cookery, it is considered one of the essential herbs; along with parsley, rosemary and thyme. Poultry and pork packed with sage-and-onion stuffing are traditional festive fare.

As a flavouring, common sage withstands long cooking times, but if too much is used it may become bitter. Sage flavours are due to essential oils, a chemical cocktail of terpenes such as cineole, borneol, and thujone. The occurrence of thujone, a chemical capable of causing muscle spasms, has raised concerns that common sage may be toxic at high concentrations.

Gardeners have selected many different sorts of common sage for their aesthetic appearances. By the end of the seventeenth century, nearly a dozen sorts of common sage were being grown in the Oxford Physic Garden. There were sorts with yellow leaves, red leaves, and broad and small leaves; there were even variegated sorts.

Further reading

Corsi GS and Bottega S 1999. Glandular hairs of Salvia officinalis: new data on morphology, localization and histochemistry in relation to function. Annals of Botany 84: 657-664.

Kintzios S 2000. Sage: the genus Salvia. CRC Press.

Walker JB and Sytsma KJ 2007. Staminal evolution in the genus Salvia (Lamiaceae): molecular phylogenetic evidence for multiple origins of the staminal lever. Annals of Botany 100: 375-391.

Stephen Harris