Lavandula

Lavender, the common name for the genus *Lavandula*, includes 39 species of flowering perennials belonging to the sage family, Lamiaceae. These plants are naturally found from the Iberian Peninsula and Mediterranean coastline—including the Adriatic and coastal North Africa—through the Middle East and into the Indian subcontinent. In temperate climates, they are widely grown as ornamentals, culinary herbs, and for commercial essential oil extraction.

The genus contains annuals, short-lived herbaceous perennials, and shrub-like plants, including subshrubs and small shrubs. Leaf shapes vary considerably: some cultivated species have simple leaves, while others feature pinnately toothed or pinnate leaves, sometimes multiply divided. Most leaves are covered in fine hairs that hold essential oils. Flowers grow in whorls on spikes above the foliage; some species have branched spikes or colored bracts at the inflorescence tips. Wild species produce blue, violet, or lilac flowers, occasionally blackish purple or yellowish. The calyx is tubular, and the corolla is also tubular, typically with five lobes—the upper lip often split, the lower lip with two clefts.

Lavender oil contains about 93 identified phytochemicals. Major components include linalyl acetate (30–55%), linalool (20–35%), tannins (5–10%), and caryophyllene (8%). Minor compounds include sesquiterpenoids, perillyl alcohols, esters, oxides, ketones, cineole, camphor, beta-ocimene, limonene, caproic acid, and caryophyllene oxide. These proportions vary significantly among species.

In Roman times, *L. stoechas*, *L. pedunculata*, and *L. dentata* were already known. During the Middle Ages, European species were split into two groups—*Stoechas* (including *L. stoechas*, *L. pedunculata*, *L. dentata*) and *Lavandula* (including *L. spica* and *L. latifolia*)—until Carl Linnaeus merged them. In *Species Plantarum* (1753), he recognized only five species: *L. multifida* and *L. dentata* from Spain, and *L. stoechas* and *L. spica* from Southern Europe, with *L. pedunculata* included under *L. stoechas*. By 1790, *L. pinnata* and *L. carnosa* were recognized (the latter later moved to *Anisochilus*). In 1826, Frédéric Charles Jean Gingins de la Sarraz listed 12 species in three sections; by 1848, 18 species were known. Dorothy Chaytor’s 1937 classification at Kew proposed six sections for 28 species, though many intermediates remained unassignable. Her sections were Stoechas, Spica, Subnudae, Pterostoechas, Chaetostachys, and Dentatae. All major cultivated and commercial forms fell within Stoechas (four species: *L. stoechas*, *L. dentata*, *L. viridis*, *L. pedunculata*) and Spica (three species: *L. officinalis*—now *L. angustifolia*—*L. latifolia*, *L. lanata*). She believed garden varieties were hybrids between true lavender (*L. angustifolia*) and spike lavender (*L. latifolia*).

The genus has three subgenera. Subgenus *Lavandula* consists mainly of woody shrubs with entire leaves, includes the main ornamental and oil-producing species, and ranges across the Mediterranean to northeast Africa and western Arabia. Subgenus *Fabricia* includes shrubs and herbs, distributed from the Atlantic to India, and contains some ornamentals. Subgenus *Sabaudia* has two distinct species from the southwest Arabian peninsula and Eritrea, sometimes placed in their own genus *Sabaudia*. Numerous hybrids and cultivars also exist. The first major clade corresponds to subgenus *Lavandula*, the second to *Fabricia*; the *Sabaudia* group is less clearly defined. Within the *Lavandula* clade, subclades match existing sections but place Dentatae separately from Stoechas. Within *Fabricia*, subclades correspond to Pterostoechas, Subnudae, and Chaetostachys. The current classification (Upson and Andrews, 2004) includes 39 species in 8 sections (the original 6 plus 2 new ones) across 3 subgenera. Because lavender cross-pollinates easily, countless variations make classification difficult.

The English word “lavender” dates to the 13th century and likely comes from Old French *lavandre*, from Latin *lavare* (to wash), referring to blue infusions used for bathing. Linnaeus’s botanical name *Lavandula* is thought to derive from this and other European vernacular names. Common names like “English lavender,” “French lavender,” and “Spanish lavender” are imprecisely applied. “English lavender” usually refers to *L. angustifolia*, though some call it “Old English lavender.” “French lavender” may mean either *L. stoechas* or *L. dentata*. “Spanish lavender” can refer to *L. pedunculata*, *L. stoechas*, or *L. lanata*.

The most commonly cultivated form is common or English lavender (*Lavandula angustifolia*, formerly *L. officinalis*), with many cultivars. Other popular ornamental species include *L. stoechas*, *L. dentata*, and *L. multifida* (Egyptian lavender). Because cultivated forms are planted worldwide, they occasionally escape and naturalize.