Many species are found in alpine or sub-alpine meadows where snow is common. Flowers usually are borne terminally, are zygomorphic, and have a lower petal shaped like a lip. The most common flower colours are purple, blue-white, and violet. Some species have yellow markings on the lower petal to act as a guide to pollinating insects.
Alternative names, mainly in herbalism, are Augentrostkraut, Euphrasiae herba, Herba Euphrasiae and Herbe d'Euphraise.
The plant was known to classical herbalists, but then was not referred to until mentioned again in 1305. Nicholas Culpeper assigned it to the Zodiac sign Leo, claiming that it strengthened the brain. It was also used to treat bad memory and vertigo.[1]
In the Elizabethan era, the plant was used in ales, and Gervase Markham's Countrie Farm (1616) said that one should "Drinke everie morning a small draught of Eyebright wine."[2]
Parts used include the leaf, the stem, and small pieces of the flowers. Typical preparations include a warm compress, or tea. Eyebright preparations are also available as an extract or capsule.
From the presence of secondary metabolites, an astringent and anti-inflammatory activity can be hypothesized for Euphrasia preparations. The ocular use of Euphrasia is based upon tradition. However, since the efficacy of the claimed ocular uses is undocumented and external eye application is not hygienic, therapeutic use cannot be recommended.[3]
The phylogeny of the genera of Rhinantheae has been explored using molecular characters.[4][5]Euphrasia belongs to the core Rhinantheae. Euphrasia is the sister genus to Odontites, Bellardia, Tozzia, and Hedbergia. In turn, these five genera share phylogenetic affinities with Bartsia.
The genus Euphrasia is taxonomically complicated due to many species being interfertile and prone to hybridisation. Despite there having been a number of taxonomic revisions[6][7][8] the appropriate rank of many taxa, as well as the relationships between them, remains unclear.
^ abTěšitel, Jakub; Říha, Pavel; Svobodová, Šárka; Malinová, Tamara; Štech, Milan (2010-10-28). "Phylogeny, life history evolution and biogeography of the rhinanthoid Orobanchaceae". Folia Geobotanica. 45 (4): 347–367. doi:10.1007/s12224-010-9089-y. S2CID39873516.
^ abScheunert, Agnes; Fleischmann, Andreas; Olano-Marín, Catalina; Bräuchler, Christian; Heubl, Günther (2012-12-14). "Phylogeny of tribe Rhinantheae (Orobanchaceae) with a focus on biogeography, cytology and re-examination of generic concepts". Taxon. 61 (6): 1269–1285. doi:10.1002/tax.616008.
^Yeo, P. F. (1978). "A taxonomic revision of Euphrasia in Europe". Botanical Journal of the Linnean Society. 77 (4): 223–334. doi:10.1111/j.1095-8339.1978.tb01401.x.
^Sell, P. D.; Yeo, P. F. (1970). "A revision of the North American species of Euphrasia L. (Scrophulariaceae)". Botanical Journal of the Linnean Society. 63 (3): 189–234. doi:10.1111/j.1095-8339.1970.tb02320.x.
