The genus is distributed throughout theOld World and the Americas (over 900 total species), with three distinct regions of diversity: Central America and South America (approximately 600 species); Central Asia and the Mediterranean (250 species); Eastern Asia (90 species).[5]
The nameSalvia derives fromLatinsalvia (sage), fromsalvus (safe, secure, healthy), an adjective related tosalūs (health, well-being, prosperity or salvation), andsalvēre (to feel healthy, to heal).[8]Pliny the Elder was the first author known to describe a plant called "Salvia" by the Romans, likely describing thetype species for the genusSalvia,Salvia officinalis.
The common modern English namesage derives fromMiddle Englishsawge, which was borrowed fromOld Frenchsauge, from Latinsalvia (the source of the botanical name).[8][9][10] When used without modifiers, the name "sage" generally refers toSalvia officinalis ("common sage" or "culinary sage"), although it is used with modifiers to refer to any member of the genus.[8] Theornamental species are commonly referred to by their genus nameSalvia.[8]
Salvia species include annual,biennial, or perennial herbaceous plants, along withwoodysubshrubs. Thestems are typically angled like other members in Lamiaceae. The leaves are typically entire, but sometimes toothed orpinnately divided. The flowering stems bear smallbracts, dissimilar to the basal leaves—in some species the bracts are ornamental and showy.
The flowers are produced inracemes orpanicles, and generally produce a showy display with flower colors ranging from blue to red, with white and yellow less common. Thecalyx is normally tubular or bell shaped, without bearded throats, and divided into two parts or lips, the upper lip entire or three-toothed, the lower two-cleft. Thecorollas are often claw shaped and are two-lipped. The upper lip is usually entire or three-toothed. The lower lip typically has two lobes. Thestamens are reduced to two short structures with anthers two-celled, the upper cell fertile, and the lower imperfect. The flowerstyles are two-cleft. The fruits are smooth ovoid or oblongnutlets and in many species they have amucilaginous coating.[11]
Many members ofSalvia havetrichomes (hairs) growing on the leaves, stems and flowers, which help to reduce water loss in some species. Sometimes the hairs are glandular and secrete volatile oils that typically give a distinct aroma to the plant. When the hairs are rubbed or brushed, some of the oil-bearing cells are ruptured, releasing the oil. This often results in the plant being unattractive tograzing animals and someinsects.[6]
The defining characteristic of the genusSalvia is the unusualpollination mechanism. It is central to any investigation into thesystematics, species distribution, orpollination biology ofSalvia. It consists of two stamens (instead of the typical four found in other members of the tribe Mentheae) and the twothecae on each stamen are separated by an elongate connective which enables the formation of the lever mechanism.[12] Sprengel (1732) was the first to illustrate and describe the nototribic (dorsal) pollination mechanism in Salvia.[13] When apollinator probes a male stage flower fornectar, (pushing the posterioranthertheca) the lever causes the stamens to move and thepollen to be deposited on the pollinator. When the pollinator withdraws from the flower, the lever returns the stamens to their original position. In older, female stage flowers, thestigma is bent down in a general location that corresponds to where the pollen was deposited on the pollinator's body. The lever of mostSalvia species is not specialized for a single pollinator, but is generic and selected to be easily released by many bird and bee pollinators of varying shapes and sizes.[14] The lever arm can be specialized to be different lengths so that the pollen is deposited on different parts of the pollinator's body.[12][15] For example, if a bee went to one flower and pollen was deposited on the far back of her body, but then it flew to another flower where the stigma was more forward (anterior), pollination could not take place. This can result in reproductive isolation from the parental population and new speciation can occur.[12] It is believed that the lever mechanism is a key factor in the speciation, adaptive radiation, and diversity of this large genus.[12]
George Bentham was first to give a fullmonographic account of the genus in 1832–1836, and based his classifications on staminal morphology.[16] Bentham's work on classifying the familyLabiatae (Labiatarum Genera et Species (1836)) is still the only comprehensive and global organization of the family. While he was clear about the integrity of the overall family, he was less confident about his organization ofSalvia, the largest genus in Labiatae (also called Lamiaceae). Based on his own philosophy of classification, he wrote that he "ought to have formed five or six genera" out ofSalvia. In the end, he felt that the advantage in placing a relatively uniform grouping in one genus was "more than counterbalanced by the necessity of changing more than two hundred names." At that time there were only 291 knownSalvia species.[6]
Bentham eventually organizedSalvia into twelve sections (originally fourteen), based on differences in corolla, calyx, and stamens. These were placed into four subgenera that were generally divided intoOld World andNew World species:
SubgenusSalvia: Old World (sections: Hymenosphace, Eusphace, Drymosphace)
SubgenusSclarea: Old World (sections: Horminum, Aethiposis, Plethiosphace)
SubgenusCalosphace: New World (section: Calosphace)
SubgenusLeonia: Old and New World (sections: Echinosphace, Pycnosphace, Heterosphace, Notiosphace, Hemisphace)
His system is still the most widely studied classification ofSalvia, even though more than 500 new species have been discovered since his work. Other botanists have since offered modified versions of Bentham's classification system, while botanists in the last hundred years generally do not endorse Bentham's system.[6]
It was long assumed thatSalvia's unusual pollination and stamen structure had evolved only once, and that thereforeSalvia wasmonophyletic, meaning that all members of the genus evolved from one ancestor. However, the immense diversity in staminal structure, vegetative habit, and floralmorphology of the species withinSalvia has opened the debate about itsinfrageneric classifications.
Through DNA sequencing,Salvia was shown to not be monophyletic but to consist of three separateclades (Salvia clades I–III) each with differentsister groups.[5] They also found that the staminal lever mechanism evolved at least two separate times, throughconvergent evolution.[5] Walker and Sytsma (2007)[17] clarified this parallel evolution in a later paper combining molecular and morphological data to prove three independent lineages of theSalvia lever mechanism, each corresponding to a clade within the genus. It is surprising to see how similar the staminal lever mechanism structures are between the three lineages, soSalvia proves to be an interesting but excellent example of convergent evolution.
Walker and Sytsma (2007) also addressed the question of whetherSalvia is trulypolyphyletic or justparaphyletic within the tribe Mentheae.[17] To makeSalvia monophyletic would require the inclusion of 15 species fromRosmarinus,Perovskia,Dorystaechas,Meriandra, andZhumeriagenera. The information attained by Walker and Sytsma (2007) supporting the three independent origins of the staminal lever indicate thatSalvia is not the case where 15 species (currently not members of the genus) are actually members ofSalvia but underwent character reversals—in other words,Salvia is paraphyletic as previously circumscribed. In 2017 Drew et al.[18] recircumscribedSalvia, proposing that the five small embedded genera (Dorystaechas,Meriandra,Perovskia,Rosmarinus, andZhumeria) be subsumed into a broadly definedSalvia. This approach would require only 15 name changes whereas maintaining the five small genera and renaming variousSalvia taxa would require over 700 name changes.
Thecircumscription of individual species withinSalvia has undergone constant revision. Many species are similar to each other, and many species have varieties that have been given different specific names. There have been as many as 2,000 named species and subspecies. Over time, the number has been reduced to less than a thousand. A modern and comprehensive study ofSalvia species was done by Gabriel Alziar, in hisCatalogue Synonymique desSalvia du Monde (1989) (World Catalog ofSalvia Synonyms). He found that the number of distinct species and subspecies could be reduced to less than 700.[6][19]
Salvia farinacea ×Salvia longispicataMystic Spires Blue 'Balsalmisp'Woodland sage (Salvia nemorosa) in Austria
Many species are used asherbs, as ornamental plants (usually for flower interest), and sometimes for their ornamental and aromatic foliage. Some species, such asSalvia columbariae andSalvia hispanica, are also grown for their seeds. The Plant List has 986 accepted species names.[20] A selection of some well-known species is below.
Salvia apiana: white sage; sacred to a number ofNative American peoples, and used by some tribes in their ceremonies
Salvia species are used as food plants by thelarvae of someLepidoptera (butterfly andmoth) species including thebucculatricid leaf-minerBucculatrix taeniola which feeds exclusively on the genus[23] and theColeophora case-bearersC. aegyptiacae,C. salviella (both feed exclusively onSalvia aegyptiaca),C. ornatipennella andC. virgatella (both recorded onSalvia pratensis).
^Sprengel, C. K. 1793. Das entdeckte Geheimnis der Natur im Bau und in der Befruchtung der Pflanzen. Friedrich Vieweg dem aeltern, Berlin, Germany.
^Classen-Bockhoff R; Crone M; Baikova E (2004). "Stamen development in Salvia L.: Homology reinvestigated".International Journal of Plant Sciences.165 (4):475–498.doi:10.1086/386565.S2CID83554246.
^Classen-Bockhoff R, Tweraser E, Wester P. 2003. The staminal lever mechanism in Salvia L. (Lamiaceae) – a review. Plant Biology 5: 33–41.
^El-Gazzar, A.; Watson, L.;Williams, W. T.; Lance, G. N. (1968). "The taxonomy of Salvia: a test of two radically different numerical methods".Botanical Journal of the Linnean Society.60 (383):237–50.doi:10.1111/j.1095-8339.1968.tb00087.x.
^Drew, B. T., González-Gallegos, J. G., Xiang, C. L., Kriebel, R., Drummond, C. P., Walker, J. B. and Sytsma, K. J., 2017. "Salvia united: The greatest good for the greatest number".Taxon, 66(1), pp. 133–145.doi:10.12705/661.7
