Salvia rosmarinus (/ˈsælviə ˌrɒsməˈraɪnəs/[3][4]), commonly known as rosemary, is a shrub with fragrant, evergreen, needle-like leaves and white, pink, purple, or blue flowers.

[9] It is considered a potentially invasive species and its seeds are often difficult to start, with a low germination rate and relatively slow growth, but the plant can live as long as 35 years.

[12] The leaves are evergreen, 2–4 cm (3⁄4–1+1⁄2 in) long and 2–5 mm (1⁄16–3⁄16 in) broad, green above, and white below, with dense, short, woolly hair.

[17] Elizabeth Kent noted in her Flora Domestica (1823), "The botanical name of this plant is compounded of two Latin words, signifying Sea-dew; and indeed Rosemary thrives best by the sea.

This mention was in a document which was later credited to Charlemagne, who promoted the general usage of herbs and ordered rosemary specifically to be grown in monastic gardens and farms.

[22] There are no records of rosemary being properly naturalized in Britain until 1338, when cuttings were sent to Queen Philippa by her mother, Countess Joan of Hainault.

Rosemary can grow quite large and retain attractiveness for many years, can be pruned into formal shapes and low hedges, and has been used for topiary.

When roasted with meats or vegetables, the leaves impart a mustard-like aroma with an additional fragrance of charred wood that goes well with barbecued foods.

[36][37] Rosemary extract has been shown to improve the shelf life and heat stability of omega 3-rich oils which are prone to rancidity.

[39] Hungary water, which dates to the 14th century, was one of the first alcohol-based perfumes in Europe, and was primarily made from distilled rosemary.

[40]Rosemary oil is used for purposes of fragrant bodily perfumes or to emit an aroma into a room; it is also burnt as incense, and used in shampoos and cleaning products.

[42] Rosemary extract, specifically the type mainly consisting of carnosic acid and carnosol, is approved as a food antioxidant preservative in several countries.

One of the studies investigating the clinical efficacy of rosemary oil in the treatment of androgenetic alopecia and comparing its effects with minoxidil 2% (a current standard of care medication), found no significant difference between study groups using either rosemary oil or minoxidil regarding hair count, either at month 3 or month 6 of treatment.

The latter talked about rosemary in his most famous writing, De Materia Medica, one of the most influential herbal books in history.

[51] In Act 4 Scene 5 of Romeo and Juliet, Friar Lawrence admonishes the Capulet household to "stick your rosemary on this fair corse, and as the custom is, and in her best array, bear her to church.