Eyebright

The Russian name “eyebright”, fixed in botany, is associated with the use of this plant in folk medicine - it was used to treat eye diseases ^[2] .

F. Wiedemann and E. Weber (1852) cite plants as “full-time grass”, “eye-glasses”, “eye socket”, “light of eyes”, and “full-time help” as Russian names ^[3] .

The Latin name used by Karl Linnaeus (and earlier Doduns , Fuchs , Lobel ) corresponds to the Greek name of the plant - εὐφρασία . Probably, it was formed on behalf of Euphrosyne ( dr. Greek εὐφροσύνη - “joy”), one of the three graces . According to another version, the name comes directly from εὐφραίνω - “to please, make happy,” which in turn is associated with φρήν - “heart, soul, mind” ^[4] . Apparently, this name is also associated with the use of eyebright for the treatment of eye diseases ^{[3] [5]} . At the direction of K. Baugin (1623), however, this name was originally used in relation to some borage , presumably cucumber grass ^[6] .

Representatives of the genus are annual herbaceous plants, rarely perennials and shrubs ^{[7] [8] [9]} . The lateral roots are thin, with haustoria serving to attach to the roots of other plants (in high mountain species, haustoria may be absent). Root hairs are few. The stem is covered with curly hairs bent downwards, branches in the lower nodes, the branches are sometimes re-branched. Cotyledon leaves are bare ^[10] . European annual pupils show two seasonal forms that differ in morphology (the so-called seasonal dimorphism): spring or early summer, weakly branching, with elongated internodes , the lower flowers are located in the fourth node of the stem; and autumn or late summer form, branching many times, with very short lower internodes, the flowers are located not lower than the 5-12th node. Among perennial species, a number of morphological forms stand out, which were proposed by the names of the most characteristic representatives:

• Malesianae type with annually dying stems with randomly spaced branches,
• Cuneata type also with dying stems with opposite branches in the axils of the leaves, while the upper branches develop earlier than the lower,
• Paradoxa type with opposite branches, the flowers on which bloom simultaneously with the flowers on the main axis, the lower branches develop earlier than the upper ones,
• Phragmostoma type with major axes developing from the nodes of last year’s axis; their upper branches develop earlier than the lower ones
• type Striata with unbranched stems, dying every year,
• Humifusa type with recumbent and rooting axes, very rarely rising,
• Collina type with stems dying to the upper branch (and not to the base), with randomly located branches ^[8] .

The leaves of most species are oppositely arranged along the stem (sometimes bracts are alternate in the upper part), sessile or almost sessile, slightly thickened, bare or pubescent, linear-lanceolate in outline, ovoid or elliptical ^[9] , along the edge with one or several pairs blunt or sharp teeth, rarely whole. Veins depressed from above and protruding from below, ending in recesses between teeth, rarely branched ^[10] . The upper stem leaves and lower bracts are often very similar in appearance, but often noticeably differ in the nature of pubescence. Important diagnostic features are the size of the leaf, the shape of the base, the number and location of the teeth along the edges, the location of the sessile glands on the underside of the leaf, the nature of the pubescence of the leaf blade ^[8] .

The flowers are zygomorphic, sessile or almost sessile (the length of the peduncle progressively decreases upward along the axis of the plant), solitary in the axils of the bracts of leaves, together form leafy apical spike-like brushes . As a rule, opposite flowers in one node bloom and wither simultaneously, however, in species without erect stems, one flower has one flower ^[8] . Bracts are large, leaf-shaped. The calyx is narrow - crowned or narrow - bell-shaped, cut in half — two-thirds of the length or stronger than four almost equal triangular lobes, unclearly two-lipped ^{[9] [4]} . The corolla is two-lipped , usually white or of varying intensity, lilac, rarely yellow, pink, blue, brown-raspberry, often with purple veins, in the tube and on the lower lip with yellow spots. The pubescence of the corolla is different, both simple and glandular hairs may be present, however this sign was not used to distinguish between European and American eyelids ^[8] . The upper lip of the corolla is helmet-shaped, with two small, integral, serrated or notched lobes, the lower lip is longer, flat, with three notched lobes. The stamens are among four, in two pairs of different lengths, the threads extend from the beginning of the corolla tube, are bent up. Anthers with two sphenoid appendages, as a rule, narrow and sharp. Threads and anthers can be lowered. The stigma of the pestle is located above the anthers, hairy, bilobate, but often looks capitate due to unclear notches between the blades or reduction of one of the blades ^[8] . The ovary is bilobate, usually pubescent, narrowly elliptical to oblong, oblate on the sides, obtuse or notched at the end, at the base from the ventral side with nectary ^{[9] [10]} . When determining the eyebright, it is necessary to consider the nature of pubescence on a flower cup ^[8] .

The fetus is a loculicidal capsule , as a rule, with 8–20 dark grayish seeds of a broad-spindle or elliptical shape, with 8–14 longitudinal whitish scars and small transverse stripes ^{[10] [4]} . The shape of the box when viewed from above in all species is from ovoid to elliptical, with a long narrow pointed tip, and when viewed from the side, it is more diverse: broadly obovate, obliquely heart-shaped, oblong, ovoid-elliptical, ovoid, narrow-ovoid, in some species, the box is bicorn. The nature of pubescence is an important diagnostic feature. The size of the fruit progressively decreases from the base of the plant to the top, the latest fruit is tied much lower in the plant than the latest flower is formed ^[8] .

The base number of chromosomes is x = 11 ^[4] . The diploid set is, as a rule, 2n = 22, 44 ^[9] , less often 88 or more ^[8] .

The shoots of eyebright are morphologically similar. Hypocotyl (subcotyledonous part) naked, grassy. The cotyledons are sessile or almost sessile, elliptically oblong, with a wedge-shaped base and a rounded end, glabrous, grassy. Epicotyl (supranocotyledonous internode) grassy, ​​with unicellular hairs ^{[11] [12]} .

Most species are predominantly cross-pollinated plants, in which the anthers of the stamens and stigmas of the pestle are bred in space, however, some small-flowered European eyelids are self-pollinated ; when flowering, their anthers are located directly above the stigma of the pestle ^[8] . Apomixis does not occur in eyebright ^[13] .

Many species of the genus are extremely variable, and from year to year the characters within the same population can vary significantly. As an example of an illustration of such variability, a population of small euphrasia with an unusual coloration of the corolla and with a narrow lower lip, is one and a half times longer than the norm. These characters persisted in the population for four years of observation, for which the number of plants in it increased significantly. However, after 19 years, not a single plant with the indicated characteristics was found. A similar variability is observed in the pupils according to the degree of pubescence, the shape of the leaves, the color intensity of the corolla and other signs ^[14] .

The phytochemistry of pupils has been poorly studied. Studies of European species have shown up to 12% tannins in plants. Of these, iridoid glycosides are distinguished: aucubin (about 0.5%), catalpole , euphroside , ixoroside ; flavonoid glycosides: quercetin , apigenin ^[15] phenolic acids: caffeic and ferulic ^[16] .

Eyebright is not mentioned among medicinal plants neither in Galen , nor in Pliny , nor in Dioscorides . Probably the earliest mention of the medicinal properties of euphrasia dates back to 1305, when Bernard de Gordon Lilium medicinae recommended both internal and external use of eyebright for eye treatment. Arnold of Villanova in the work of Vini Euphrasiati tantopere celebrati of the beginning of the 14th century described the enlightenment of people who had not seen for a long time after eye treatment with eye-opening. According to K. Baugin, its healing properties for curing eye diseases were well known by about 1380 ^[17] .

In the doctrine of signatures according to William Coles (1657) purple and yellow spots on eyebright flowers are compared with bruising on the eyes during an illness. Also, according to Coles, many authors noted that birds, namely carduelis , linnet and some others, use eyebright to treat diseases of their own eyes and the eyes of chicks ^[18] .

Eyebright was considered a cure for virtually all eye diseases. William Woodville (1792) wrote: “Eyebright owes its name to the power attributed to it against various eye diseases, for the treatment of which it was used both externally and internally, and was praised as if it wereverum oculorum solamen . However, since it is impossible to have a single cure for all eye diseases, the absurd and incompetent recommendations for using eyebright as such should not be particularly taken into account by practitioners of rational medicine. It is necessary, however, to note that some authors have identified very specific eye diseases, in the use of which for the treatment of eyelid, presumably, was the most effective. " Woodville, however, noted that "not a single modern evidence has been found of the effectiveness of euphrasia" ^[19] .

In Russia, drugs from eyebright were prescribed for the treatment of jaundice, stomach diseases. In folk medicine, eye infusion, fresh juice, vodka tinctures were used to treat eye diseases; To combat abdominal pain, angina pectoris , hernia compresses were used from the eyebright, the plant was also taken orally. In the second half of the 20th century, the plant was used mainly to treat inflammation of the eyes, spotting of the cornea, gastritis and enteritis, tumors and purulent formations, to improve cardiac activity. In homeopathy, the essence of eyebright is used against conjunctivitis ^[20] .

In addition to its use in medicine, the eye was brewed in tea and used to make wine and ale ^[17] .

The formation of haustoriums in plants from the rattle tribe ( rattles , serratus , marianian ) was discovered in 1847 by Joseph Decken , who pointed out their parasitization on cereals, shrubs and trees. In the same year, John Henslow discovered them at the eyebright ^[21] .

Ludwig Koch in 1891 showed that the eyeglasses are attached by haustoria to the thinnest young roots of the host plant, while species of barnate are attached to the already dead roots of the host and use dead substance. Richard Wetstein noted that determining the host plant for euphrasia is often difficult, because by the time the euphrasia blooms, its thin roots often die and the parasite continues to feed on saprophytic ^[21] . The structure of the roots and haustoriums of the eye was studied in detail by Koch (1891), Wettstein (1896) and Naidhardt (1947). Najdhardt noted that the roots of plants without a host plant penetrate quite deeply into the soil, and if it is present, the root root is short and highly branched ^[21] .

Koch was the first to investigate the possibility of growing traps in a pot. The pupils successfully germinated, however, in the absence of a host plant, they developed very slowly. Single plants died in 3-4 weeks, and plants that were surrounded by other individuals during uneven sowing could sometimes bloom. Such plants used individuals of their own species as hosts, attaching haustoria to their roots. Based on these observations, Koch considered the presence of a host a necessary condition for the development of an euphorbia ^[22] . P. Io in 1961 noted cases of attachment of haustorium pups to their own roots ^[21] .

In 1897, Wettstein was able to obtain among the numerous plants eyeballs, transplanted into separate pots, one or several plants after germination, flowering and fruiting plants. Some of them were attached by haustoria to the roots of the enigma surrounding them, and some were completely devoid of haustoria. Thus, in his opinion, although the presence of a host plant contributes to the rapid growth and development of pupils, plants capable of multiplying can develop without it ^[22] .

In 1896-1899, Emil Heinricher conducted experiments with three types of spectacles . Direct eyeball plants developed faster if they were surrounded by other individuals of the species, while only a few of them could bloom. The eyebright formed numerous buds, of which only a few developed into prolific flowers. The eyebright, small without a host, developed quite normally and flourished without forming haustoriums, although such plants were inferior in size to plants with a host. Based on these experiments, Heinricher called the euphrasia officinalis the most progressive parasite of the three, and the small euphoria the least progressive, emphasizing that specimens of this species are often found in nature without a host ^[22] .

In 1910, Heinricher published the results of cultivation of these three species with different hosts. He noted that their cultivation is not difficult subject to summer or autumn planting of seeds, limiting the growth of the host plant and providing adequate lighting. Moreover, a wide variety of species can be used as hosts ^[22] .

Studies by P. Io in the 1960s confirmed the possibility of growing pups with or without a host, as well as the fact that plants without a host, both in nature and under artificial conditions, although they are smaller than their counterparts, can it is quite normal to bloom and bear fruit ^[22] .

Eyebright is found in temperate and boreal zones of both hemispheres: in Europe and the Azores , in North and Central Asia , in northwestern Africa , in North America , as well as in South America , Borneo and New Guinea , Australia and New Zealand ^{[8] [23] [4]} .

Specification centers are confined to mountainous regions: the Alps , the mountains of Australia and New Zealand ^[9] .

Род Euphrasia у Карла Линнея

Действительное описание рода Euphrasia было опубликовано Карлом Линнеем в 5-м издании Genera plantarum (1754):

659. Euphrasia. * Tournef. 78. Odontitis Dill. gen. 6.

Чашечка . Околоцветник цельный, трубчатый, четырёхлопастный, асимметричный, не опадающий.

Венчик сросшийся, раскрытый. Трубка длиннее чашечки. Верхняя губа вогнутая, выемчатая. Нижняя губа поникшая, трёхлопастная; лопасти равные, тупые.

Тычинки в числе четырёх, нитевидные, под верхней губой изогнутые. Пыльники двулопастные, нижняя их лопасть с заострённым шиповидным концом.

Пестик . Завязь яйцевидная. Столбик нитевидный, сходный с тычинками. Рыльце тупое, цельное.

Плод . Коробочка яйцевидно-продолговатая, сплюснутая, двугнёздная.

Семена многочисленные, мелкие, почти округлые.

Original text (lat.)

Cal. Perianthium monophyllum, tubulatum, quadrifidum, inæquale, persistens.

Cor. monopetala, ringens. Tubus longitudine calycis. Labium superius concavum, emarginatum; Lab. inferius patens, tripartitum: laciniis æqualibus, obtusis.

Stam. Filamenta quatuor, filiformia, sub labio superiore inclinata. Antheræ bilobæ: quarum inferiores lobo inferiore in spinulam acuminatæ.

Pist. Germen ovatum. Stylus filiformis, situ & figura staminum. Stigma obtusum, integrum.

Per. Capsula ovato-oblonga, compressa, bilocularis.

Sem. numerosa, minima, subrotunda.

— Linnaeus, C. Genera plantarum. — Editio quinta ab auctore reformata et aucta. — Holmiæ: Laurentii Salvii, 1754. — P. 263. — xxxii + 500 p.

В фундаментальном труде Species plantarum (1753) Линней отнёс к роду 6 видов, из которых только 2 относятся к роду в настоящее время:

• Euphrasia latifolia L., 1753 — Parentucellia latifolia (L.) Caruel , 1885 — Парентучеллия широколистная — один из трёх видов Parentucellia , встречается на каменистых и песчаных склонах в Европе от Франции до Турции.
• Euphrasia officinalis L., 1753 — Очанка лекарственная — лектотип рода. Широко распространённое в Европе, весьма изменчивое растение.
• Euphrasia tricuspidata L., 1753 — эндемик Северо-Восточной Италии ( Трентино — Альто-Адидже , Венеция ).
• Euphrasia odontites L., 1753 — Odontites vulgaris Moench , 1794 — Зубчатка обыкновенная — широко распространённое растение, встречающееся на лугах и в лесах по всей Евразии.
• Euphrasia lutea L., 1753 — Euphrasia linifolia L., 1753 — Odontites luteus (L.) Clairv. , 1811 — Зубчатка жёлтая — встречается на лугах и склонах в Европе и Предкавказье.

Более поздние работы по систематике очанок

Английский ботаник Дж. Бентам в 1846 году выделил внутри рода три группы неопределённого ранга — Semicalcaratae («неясно шпорценосные»), Australes («южные») и Trifidae («трёхраздельные»), — отличавшиеся характером опушения и формой пыльников, а также формой листьев.

В 1879 году Дж. Гукер описал из Новой Зеландии вид Euphrasia disperma и поместил его в новый подрод Anagospermae (от др.-греч. ἀνάγω — «выдвинуть, приподнять» и σπέρμα — «семя»). Этот подрод разительно отличается от других очанок завязями с 2—4 семязачатками, одиночными цветками с очень длинной трубкой венчика, исключительно распростёртыми побегами. В 1895 году Рихард Веттштейн возвёл подрод Гукера в ранг рода Anagosperma . Однако до этого, в 1881 году Дж. Армстронг описал по скудному гербарному материалу новый род Siphonidium ( др.-греч. σίφων — « siphon ”, along a long curved pipe), in 1925 this material was assigned by T. Chizman to the eye-spot described by Hooker. In 1932, E. Du Ri doubted the possibility of at least some isolation of this species at the supraspecific level, having discovered a number of species with intermediate morphological characteristics between E. disperma and previously known spectacles ^[8] .

The monograph of the spectacles of R. Wettstein of 1896 laid the foundation for the differentiation of species of the genus. He combined Semicalcaratae and Australes as sub-sections of the Eueuphrasia section, and Trifidae took in the section rank. In the Trifidae section and the Australes subsection, Wetstein identified groups of perennial and annual species without a specific rank, and in the Semicalcaratae section, the groups Parviflorae (“small-flowered”), Grandiflorae (“large-flowered”) and Angustifoliae (“narrow-leaved”) were identified based on the length of the corolla tube, shape leaves and pubescent capsules. The main drawback of Wettstein's work was the absence of herbar material from Malaysia and Taiwan ^[8] .

E. Jörgensen in 1919 slightly changed the Wetstein system, elevating sections and subsections to the rank of subgenus and sections, respectively. He also singled out two subsections — Angustifoliae and Ciliatae (“ciliated”) as part of the Eueuphrasia section (corresponding to the Wetstein subsection Semicalcaratae ); the first of them corresponds to the Wetstein's informal group of the same name, the second to the other two together.

G. Pugsley in 1936 distinguished two new subsections Japonicae (“Japanese”) and Alpicolae (“alpine”) in the Semicalcaratae section, represented by species from Japan, based on life form, leaf shape, cup shape, corolla size and color, corolla pubescence , anthers and boxes. He also described the new sections of Atlanticae (“Atlantic”), in which he placed an eyelet from the Azores with a bicornate box and rounded leaves, and Paradoxae (“amazing”) with a single perennial view from the Juan Fernandez islands with whole corners of the lower lip of the corolla, unequal appendages of anthers, a box with an obscure notch at the apex and with bristly pubescent edges. Pugsley used flowering in early summer or late summer as one of the main signs of the separation of European species of eyebright ^[8] .

E. Du Ri identified a number of the most common diagnostic features for combining eyelids into intrageneric groups: pubescence and coloring of anthers, shape of corolla lobes, shape of leaves, life form. However, the Swedish botanist did not publish work with the complete system of the genus. In 1948, he singled out two new Australianienses (“Australian”) and Novaezeelandiae (“New Zealand”) sections in the Australes section, distinguished by the shape of the box.

In 1972, the D. Hartl clan system was published. He recognized five sections within the genus - Euphrasia (corresponding to Semicalcaratae and Eueuphrasia ), Australes , Trifidae , Atlanticae and Paradoxae .

The W. Barker system, published in 1982, is significantly different from the previous ones, the author distinguished 14 sections: Euphrasia (number of species not determined, type - Euphrasia officinalis L. ), Atlanticae (2 species, type - Euphrasia grandiflora Hochst. ), Malesianae ( "Malaysian", 13 species, type - Euphrasia philippinensis Du Rietz ), Cuneatae ("wedge-shaped", 2 species, type - Euphrasia cuneata G.Forst. ), Phragmostomae ("cryptorchid", the only species of Euphrasia phragmostoma WRBarker ), Pauciflorae ( rare-flowered ", 16 species, type - Euphrasia revoluta Hook.f. ), Striatae (" banded ", 4 species, type - Euphrasia striata R.Br. ), Australes (type - Euphrasia alpina R.Br. = Euphrasia collina R. Br. ), Lasiantherae ( «sherstistopylnikovye" 3 ve and type - Euphrasia lasianthera WRBarker ), Scabrae ( «Scale», 5 types, type - Euphrasia scabra R.Br. ), Novaezeelandiae (4 types, type - Euphrasia zelandica Wettst. ), Paradoxae (the only species Euphrasia formosissima Skottsb. ) , Anagospermae (4 species, type - Euphrasia disperma Hook.f. ) and Trifidae (18 species, type Euphrasia trifida Poepp. ex Benth. ) ^[8] .

Monograph processing of the genus was repeatedly carried out in certain territories: A. Chabert (1902) described the spectacles of France, G. Pugsley (1930) examined the spectacles in the UK, L.P. Sergievskaya (1935) published an article on the spectacles of Western Siberia, F. Pennell (1943 ) was engaged in the study of the spectacles of the Western Himalayas, E. Kimura (1941, 1948) and Dz. Oi (1965) published monographs of eyewear from Japan, Lee H. - Taiwan (1950) and mainland China (1953), S. V. Yuzepchuk (1955) carried out monographic processing of the genus for the book Flora of the USSR . P. Io published monographs of the genus in North America (1970, co-authored with P. Sell ) and Europe (1978) ^[8] . In 2005, the Ochanka genus system was published by G. L. Gusarova , in which 73 species of the genus are given for the territory of Russia ^[24] .

Name status of Euphrasia officinalis L.

The Linnaeus species Euphrasia officinalis L. was selected by the lectotype of the genus N. Britton and E. Brown in the 2nd edition of the Illustrated Flora of the Northern United States (1913). The choice of a number of lectotypes proposed in this work was subsequently recognized as inappropriate and redefined. However, in 1930, F. Pennell showed the validity of the decision of Britton and Brown: the description of this species in Linnaeus most closely matches the description of the genus as a whole. According to W. Stern (1952), Linnaeus compiled descriptions of plant genera, based mainly on the morphology of their most famous and (or) medicinal representative, which, obviously, is Euphrasia officinalis .

Linnaeus's description of the species is based on three plants stored on one leaf in its herbarium. Two of these plants have glandular pubescence and correspond to Euphrasia rostkoviana subsp. fennica ( Kihlm. ) Jalas . There are no indications of their origin on the herbarium sheet, which indicates their probable growth in the homeland of Linnaeus, and their morphological similarity indicates the origin of samples from one population. The third plant is devoid of glandular pubescence and is either Euphrasia stricta D.Wolff ex JFLehm. or Euphrasia nemorosa Wettst. Probably, this sample was brought by Linnaeus from Russia (this is evidenced by the symbol “∈” located next to the plant), where both of these species are found ^[25] . Sell ​​and Io in 1970 chose one of the first plants as a lectotype of Euphrasia officinalis L. ^[8] .

In the literature of the second half of the 20th century, the Linnaeus species, for convenience, due to the difficulty of isolating smaller species, was understood in a very wide volume of the “aggregate species”, which includes most species of the Euphrasia section growing in the Northern Hemisphere. In this regard, a number of authors abandoned this name as a species name in favor of Euprasia rostkoviana Hayne , and M. Smeikal (1963) also refused to identify the genus with it in favor of Euphrasia tricuspidata L. , based on two identical samples and unambiguously understood in the literature. In 1992, R. Brammit and D. Kent proposed, in accordance with widespread practice, to prescribe in the International Code of Botanical Nomenclature the permissibility of using a number of Linnaean species names as “species-aggregates” ^[26] , but the corresponding amendment to the Code was not adopted.

The systematic position of the clan

Karl Linney attributed the genus to the order Angiospermia ("angiosperms") of the Didynamia class ("with two-stamens stamens"). In the system of A. Jussieux (1789), the spectacle is assigned to the order Pediculares of the class Plantæ Dicotyledones Monopetalæ ("dicotyledonous-lobed"). J. Lamarck and O. Decandol (1806) published a description of the tribe Rhinanthaceae in the order of Rhinanthaceae , which included, among others, the genus Ochanka.

In the Engler system (1912), the genus is included in the tribe Rhinantheae Lam. & DC. subfamilies of Rhinanthoideae Beilschm. Scrophulariaceae Juss family . ( Noric ) order of Tubiflorae ( Tubiflora ). In the systems of Kronqvist (1981) and Takhtadzhyan (2009), the genus is also assigned to the Norichnikov family.

Currently, the genus Ochanka belongs to the tribe Pogremykovye ( Rhinantheae Lam. & DC. ) Of the Zarazikhov family ( Orobanchaceae Vent. ). In phylogenetics, this tribe corresponds approximately to the following treasure, shown in the inset on the right ^[27] .

Views

The world flora of the genus totals, according to various estimates, from 170 to 350 species ^[27] . In temperate regions of the Northern Hemisphere, only species of the nominative section of Euphrasia are found . Some of them:

• Euphrasia officinalis L. - Eyebright , or Eye of Rostovius
• Euphrasia parviflora Schag. - Eyebright is small-colored
• Euphrasia pectinata Ten. - Eyebright comb
• Euphrasia stricta D.Wolff ex JFLehm. - Eyebright straight

Eyebright - “eye grass” ( English euphrasy ) - is mentioned in Milton ’s poem “Lost Paradise” (1674): Archangel Michael used the eyeball and ruta to heal Adam's eyes after he tasted the forbidden fruit.

Ochanka is mentioned among medicinal plants in the poem about England by “Polyolbion” by Michael Drayton (1612) ^[18] . In the poem The School-Mistress by William Shenston (1742) and in the poem Sickness by William Thompson, (1746) also heralded the healing properties of eyebright.

• Gusarova, G.L., Abstract of the genus Euphrasia (Scrophulariaceae) of Russia and neighboring states, Botan. journal - 2005. - T. 90 , No. 7 .
• Yuzepchuk, S. V. Rod 1352. Eyebright - Euphrasia L. // Flora of the USSR : 30 tons / started at hand. and under chap. ed. V. L. Komarova . - M .; L .: Publishing House of the Academy of Sciences of the USSR , 1955. - T. 22 / ed. volumes B.K. Shishkin , E.G. Bobrov . - S. 557-640. - 861 s. - 3000 copies.
• Ochanka // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
• Barker, WR Taxonomic studies in Euphrasia L. (Scrophulariaceae). A revised infrageneric classification and a revision of the genus in Australia // Journal of the Adelaide Botanic Garden. - 1982. - Vol. 28. - P. 1-304.
• Fischer, E. Scrophulariaceae // The Families and Genera of Vascular Plants / volume editor JW Kadereit. - 2004. - Vol. VII. Flowering Plants: Dicotyledons: Lamiales (except Acanthaceae including Avicenniaceae). - P. 333-432. - ISBN 3-642-62200-3 .
• Pennell, FW 34. Euphrasia [Bauhin] Linnaeus // The Scrophulariaceae of the Western Himalayas. - Philadelphia, 1943. - P. 99-113.
• Schneeweiss, GM Phylogenetic Relationships and Evolutionary Trends in Orobanchaceae // Parasitic Orobanchaceae / DM Joel, J. Gressel, LJ Musselman (eds.). - Springer, 2013 .-- P. 243-266. - 531 p. - ISBN 3-642-38145-6 .
• Sell, PD, Yeo, PF A revision of the North American species of Euphrasia L. (Scrophulariaceae) // Botanical Journal of the Linnean Society. - 1970. - Vol. 63. - P. 189–234. - DOI : 10.1111 / j.1095-8339.1970.tb02320.x .
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• Euphrasia : information on the taxon in the Plantarium project (identifier of plants and an illustrated atlas of species). (Retrieved November 13, 2016)

•   Definition of the term " eyebright " in Wiktionary .
• Euphrasia (neopr.) . The Plant List. Version 1.1 (2013). Date of treatment November 13, 2016.