Linaria Explained

Linaria is a genus of almost 200 species of flowering plants, one of several related groups commonly called toadflax. They are annuals and herbaceous perennials, and the largest genus in the Antirrhineae tribe of the plantain family Plantaginaceae.

Taxonomy

Linaria was traditionally placed in the family Scrophulariaceae. Phylogenetic analysis has now placed it in the vastly expanded family Plantaginaceae.

Closely related genera include Nuttallanthus (American toadflaxes, recently split from Linaria), Antirrhinum (snapdragons) and Cymbalaria (ivy-leaved toadflaxes).

Cultivation

Several Linaria species are cultivated as garden plants, and some are regarded as having a weedy habit.

Common toadflax or butter-and-eggs (Linaria vulgaris), a European species which is widely introduced elsewhere and grows as a common weed in some areas.^[1]
Broomleaf toadflax or Dalmatian toadflax (Linaria genistifolia, syn. L. dalmatica), a native of southeast Europe that has become a weed in parts of North America.^[2]
Purple toadflax (Linaria purpurea), a species native to the Mediterranean region grown as a garden plant for its dark purple or pink flowers. The version with purple flowers can be mistaken for lavender. Spreads readily.
Pale toadflax (Linaria repens), a species from western Europe similar to L. purpurea, but with paler flowers.
Alpine toadflax (Linaria alpina), purple flowers with orange (or purple) lobes in the center.
Moroccan toadflax (Linaria maroccana), the flower has five lobes arranged into two lips with a spur at the end, often purple with white.

Species

The following species are recognised in the genus Linaria:^[3]

Linaria accitensis
Linaria acutiloba
Linaria aeruginea
Linaria afghanica
Linaria alaica
Linaria albifrons
Linaria algarviana
Linaria alpina
Linaria altaica
Linaria amethystea
Linaria amoi
Linaria angustissima
Linaria antilibanotica
Linaria arcusangeli
Linaria arenaria
Linaria arenicola
Linaria argillicola
Linaria armeniaca
Linaria arvensis
Linaria atlantica
Linaria azerbaijanensis
Linaria badachschanica
Linaria badalii
Linaria bamianica
Linaria becerrae
Linaria bessarabica
Linaria biebersteinii
Linaria bipartita
Linaria bipunctata
Linaria bordiana
Linaria boushehrensis
Linaria brachyphylla
Linaria bubanii
Linaria bungei
Linaria buriatica
Linaria caesia
Linaria capraria
Linaria cavanillesii
Linaria chalepensis
Linaria clementei
Linaria confertiflora
Linaria corifolia
Linaria × cornubiensis
Linaria cossoniana
Linaria cossonii
Linaria cretacea
Linaria dalmatica
Linaria damascena
Linaria decipiens
Linaria depauperata
Linaria diffusa
Linaria dissita
Linaria × dominii
Linaria dumanii
Linaria elegans
Linaria elymaitica
Linaria fallax
Linaria farsensis
Linaria fastigiata
Linaria faucicola
Linaria fedorovii
Linaria ficalhoana
Linaria flava
Linaria genistifolia
Linaria gharbensis
Linaria glacialis
Linaria glauca
Linaria golestanensis
Linaria grandiflora
Linaria griffithii
Linaria grjunerae
Linaria guilanensis
Linaria haelava
Linaria hepatica
Linaria heratensis
Linaria hirta
Linaria hohenackeri
Linaria huteri
Linaria × hybrida
Linaria iconia
Linaria ikonnikovii
Linaria imzica
Linaria incarnata
Linaria incompleta
Linaria intricata
Linaria iranica
Linaria × jalancina
Linaria japonica
Linaria jaxartica
Linaria joppensis
Linaria kavirensis
Linaria khalkhalensis
Linaria khorasanensis
Linaria × kocianovichii
Linaria kokanica
Linaria kulabensis
Linaria kurdica
Linaria latifolia
Linaria laxiflora
Linaria leptoceras
Linaria lineolata
Linaria loeselii
Linaria longicalcarata
Linaria macrophylla
Linaria macroura
Linaria maroccana
Linaria maymanica
Linaria mazandaranensis
Linaria melampyroides
Linaria melanogramma
Linaria meyeri
Linaria michauxii
Linaria micrantha
Linaria microsepala
Linaria multicaulis
Linaria munbyana
Linaria musilii
Linaria nachitschevanica
Linaria nigricans
Linaria nivea
Linaria nurensis
Linaria nuristanica
Linaria oblongifolia
Linaria odora
Linaria oligantha
Linaria × oligotricha
Linaria onubensis
Linaria orbensis
Linaria ordubadica
Linaria pamirica
Linaria paradoxa
Linaria parviracemosa
Linaria pedicellata
Linaria pedunculata
Linaria pelisseriana
Linaria peloponnesiaca
Linaria peltieri
Linaria pinifolia
Linaria platycalyx
Linaria polygalifolia
Linaria popovii
Linaria propinqua
Linaria pseudolaxiflora
Linaria pseudoviscosa
Linaria purpurea
Linaria pyramidalis
Linaria qartobensis
Linaria quasisessilis
Linaria reflexa
Linaria remotiflora
Linaria repens
Linaria ricardoi
Linaria riffea
Linaria × rocheri
Linaria rubioides
Linaria sabulosa
Linaria salangensis
Linaria salzmannii
Linaria saposhnikovii
Linaria saturejoides
Linaria saxatilis
Linaria schelkownikowii
Linaria schirvanica
Linaria semialata
Linaria × sepium
Linaria sessilis
Linaria simplex
Linaria spartea
Linaria striatella
Linaria supina
Linaria tarhunensis
Linaria tenuis
Linaria thibetica
Linaria thymifolia
Linaria tingitana
Linaria tonzigii
Linaria triornithophora
Linaria triphylla
Linaria tristis
Linaria tursica
Linaria unaiensis
Linaria × valdesiana
Linaria venosa
Linaria ventricosa
Linaria veratrifolia
Linaria verticillata
Linaria virgata
Linaria viscosa
Linaria volgensis
Linaria vulgaris
Linaria warionis
Linaria weilleri
Linaria yunnanensis
Linaria yusufeliensis
Linaria × zaborskiana
Linaria zaissanica

Etymology

The members of this genus are known in English as toadflax, a name shared with several related genera. The 'toad' in toadflax may relate to the plants having historically been used to treat bubonic plague, a false link having been drawn between the words 'bubo' and 'Bufo'. The scientific name Linaria means "resembling linum" (flax), which the foliage of some species superficially resembles.

Distribution and habitat

The genus is native to temperate regions of Europe, northern Africa and Asia, with the highest species diversity in the Mediterranean region.

Ecology

Some Linaria are regarded as noxious weeds. They are likely toxic to livestock, but ruminants generally avoid them.^[4]

Chemical composition

Linaria species are rich in alkaloids, iridoids, terpenes, phenolic acids and flavonoids.

Vasicine, Vasicinone, 7-hyrdoxyvasicine, Linarinic acid, Choline, Linavuline, Luteolin, Acacetin, Apigenin, Chrysin, Quercetin, Myricetin, Linarioside, Aucubin, Linaride, Iridolinaroside A-D, Iridolinarin A-C are some compounds found in plants of this genus.^[5]

Uses

Toadflaxes are used as food plants by the larvae of some Lepidoptera species, including the mouse moth (Amphipyra tragopoginis) and the common buckeye (Junonia coenia).

Traditional medicine

Linaria vulgaris has been used as a medicinal herb.^[6]

Bibliography

A Phylogeny of Toadflaxes (Linaria Mill.) Based on Nuclear Internal Transcribed Spacer Sequences: Systematic and Evolutionary Consequences. Mario Fernández-Mazuecos, José Luis Blanco-Pastor, and Pablo Vargas. International Journal of Plant Sciences, Vol. 174, No. 2 (February 2013), pp. 234–249 Published by: The University of Chicago Press, Article DOI: 10.1086/668790
Vargas P, JA Rosselló, R Oyama, J Güemes. 2004 Molecular evidence for naturalness of genera in the tribe Antirrhineae (Scrophulariaceae) and three independent evolutionary lineages from the New World and the Old. Plant Systematics and Evolution 249:151–172.

Notes and References

Book: Brickell . Christopher . The Royal Horticultural Society A-Z Encyclopedia of Garden Plants . 2008 . 636 . Dorling Kindersley . United Kingdom . 9781405332965.
https://www.invasivespeciesinfo.gov/profile/dalmatian-toadflax Dalmatian Toadflax (Linaria dalmatica).
Web site: Linaria Mill. Plants of the World Online Kew Science . 2022-07-04 . Plants of the World Online . en.
Sing, S. E. and R. K. Peterson. (2011). Assessing environmental risks for established invasive weeds: Dalmatian (Linaria dalmatica) and yellow (L. vulgaris) toadflax in North America. International Journal of Environmental Research and Public Health 8(7) 2828-53.
Web site: Chemical constituents and biological activities of the genus Linaria (Scrophulariaceae).
Duke, J. A. Ethnobotanical uses: Linaria vulgaris. Dr. Duke's Phytochemical and Ethnobotanical Databases.