Salvia yangii, previously known as Perovskia atriplicifolia (), and commonly called Russian sage, is a flowering herbaceous perennial plant and subshrub. Although not previously a member of Salvia, the genus widely known as sage, since 2017 it has been included within them. It has an upright habit, typically reaching 0.5–1.2 metres (1+1⁄2–4 feet) tall, with square stems and gray-green leaves that yield a distinctive odor when crushed. It is best known for its flowers. Its flowering season extends from mid-summer to late October, with blue to violet blossoms arranged into showy, branched panicles. It is native to the steppes and hills of southwestern and central Asia. Successful over a wide range of climate and soil conditions, it has since become popular and widely planted. Several cultivars have been developed, differing primarily in leaf shape and overall height; 'Blue Spire' is the most common. This variation has been widely used in gardens and landscaping. S. yangii was the Perennial Plant Association's 1995 Plant of the Year, and the 'Blue Spire' cultivar received the Award of Garden Merit from the Royal Horticultural Society. The species has a long history of use in traditional medicine in its native range, where it is employed as a treatment for a variety of ailments. This has led to the investigation of its phytochemistry. Its flowers can be eaten in salads or crushed for dyemaking, and the plant has been considered for potential use in the phytoremediation of contaminated soil.
Description
Salvia yangii is a deciduous perennial subshrub with an erect to spreading habit. Superficially, it resembles a much larger version of lavender. Multiple branches arise from a shared rootstalk, growing to a height of 0.5–1.2 metres (1+1⁄2–4 feet), with occasional specimens reaching 1.5 m (5 ft). The mature plant may be 0.6–1.2 m (2–4 ft) across. The rigid stems are square in cross-section, and are covered by an indumentum formed by stellate, or star-shaped, trichomes and oil droplets. Especially during autumn, these hairs give the stems a silvery appearance. The grayish-green leaves are arranged in opposite pairs, and attached to the stems by a short petiole. They are generally 3–5 centimetres (1+1⁄4–2 inches) long and 0.8–2 cm (1⁄4–3⁄4 in) wide, although narrower in some populations. The overall leaf shape is oblate, a rounded shape longer than it is wide, to lanceolate, shaped like the head of a lance. They are pinnatipartite, with a deeply incised leaf margin that may be either wavy or sharp-toothed; even within a single community of S. yangii, there can be considerable variation in the details of leaf shape. Leaves near the top of branches may merge into bracts. The foliage is aromatic, especially when crushed, with a fragrance described as sage-like, a blend of sage and lavender, or like turpentine. The flowering season of S. yangii can be as long as June through October, although populations in some parts of its range, such as China, may bloom in a much more restricted period. The inflorescence is a showy panicle, 30–38 cm long (12–15 in), with many branches. Each of these branches is a raceme, with the individual flowers arranged in pairs called verticillasters. Each flower's calyx is purple, densely covered in white or purple hairs, and about 4 millimetres (1⁄8 in) long. The corolla is tube-shaped, formed from a four-lobed upper lip and a slightly shorter lower lip; the blue or violet blue petals are about 1 cm long. The style has been reported in both an exserted—extending beyond the flower's tube—form and one contained within the flower; all known examples of S. yangii in cultivation have exserted styles. Gardening author Neil Soderstrom describes the appearance of the flowers from a distance as "like a fine haze or fog". The fruits develop about a month after flowering, and consist of dark brown oval nutlets, about 2 mm × 1 mm (2⁄25 in × 1⁄25 in).
Phytochemistry The phytochemistry of Russian sage is under basic research. Analysis of its essential oil has identified over two dozen compounds, although the compounds detected and their relative prevalence have not been consistent. Most analyses have identified various monoterpenes and monoterpenoids as the dominant components, such as carene, eucalyptol, limonene, γ-terpinene, and (+)-β-thujone, although the essential oil of a sample from the Orto Botanico dell'Università di Torino had camphor as its most prevalent component. Other monoterpenes, camphene, α-pinene, and β-pinene are also present, as are sesquiterpenes such as γ-cadinene, δ-cadinene, trans-caryophyllene, and α-humulene. Several terpenoid alcohols—borneol, cedrol, and menthol—have been extracted, as have caffeic acid and ferulic acid. More complex compounds have been isolated, some of which were first identified in this manner, including perovskatone; the glycosides atriplisides A and B; and atricins A and B, a pair of triterpenes that are similar to oleanane. Four diterpene glucosides have been isolated by extraction.
Similar species Nine species are recognised within Salvia subg. Perovskia. S. abrotanoides shares much of the range of S. yangii, but is distinguished by its bipinnate leaves. Hybrids between these two species may occur naturally. Restricted to Turkestan in its native range, P. scrophularifolia is less upright; some forms have white flowers. The flowers of P. scabiosifolia are yellow.
Taxonomy Salvia yangii was described, under the name Perovskia atriplicifolia, by George Bentham in 1848, based on a specimen collected by William Griffith in Afghanistan, now preserved at the Kew Gardens herbarium as the species's holotype. The specific epithet atriplicifolia means "with leaves like Atriplex", referring to its similarity to saltbush. While commonly known as Russian sage, S. yangii is not native to Russia. A population collected in Taxkorgan Tajik Autonomous County, Kashgar Prefecture, Xinjiang, China was described as a separate species in 1987 and given the name Perovskia pamirica, but was later considered synonymous with P. atriplicifolia. In 2017, P. atriplicifolia was transferred to the genus Salvia. The combinations Salvia atriplicifolia and Salvia pamirica, however, have already been preoccupied by distinct taxa, thus new specific epithet yangii, honouring Yang Changyou, one of the authors of P. pamirica, was given to the species.
Phylogenetics
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