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.

Species

The following species are recognised in the genus Linaria:

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.

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, and iridolinarin A-C are some compounds found in plants of this genus.

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.