Antirrhineae

The Antirrhineae are one of the 12 tribes of the Plantaginaceae family. It contains the toadflax relatives, such as snapdragons. They are probably most closely related to the turtlehead tribe (Cheloneae) and/or a large and badly resolved core group of their family including plants as diverse as water-starworts (Callitriche), foxgloves (Digitalis), and speedwell (Veronica). The Antirrhineae include about 30 genera with roughly 320 species, of which 150 are in genus Linaria. The type genus is Antirrhinum L. Most Antirrhineae are herbaceous, short-lived, perennial or annual plants growing at most about a metre/yard tall when in full flower; the maximum height of most species is half as much or less. Some are prostrate or twining. The flowers are often conspicuous, tubular with a basal appendix (spur, gibbous, or saccate) containing nectaries, and may be of any color, though yellow and blue/purple hues are most common. Multicolored flowers are a common occurrence in this tribe; a typical pattern is one conspicuous whitish or bright yellow or reddish spot at the lower outer edge of the flower tube, looking like a protruding tongue. Other characters include poricidal dehiscent capsule fruit, and the possession of iridoid glycosides. The Antirrhineae are not noted as food- or fodder plants, probably due to the iridoid content making them less than palatable. However, the tribe does not seem to contain highly poisonous plants, either; rather, use in folk medicine has been documented for a few species. While e.g. common toadflax (Linaria vulgaris) is credited with a range of uses by European herbalists, as of the 2010s, little scientific study has been made and the traditionally attested medical properties of the Antirrhineae are by and large unremarkable by standards of the Plantaginaceae, which abound with species of major pharmacological interest. The chief human use of the present tribe is for the flowers, primarily as ornamental plants in gardening. Colloquially called 'the snapdragon', Antirrhinum majus is probably the single most widely known member of the Antirrhineae by far. A. majus cultivars can today be encountered essentially anywhere between Earth's polar circles, whether grown in a range of sizes and colours by hobbyists or field-scale for sale as cut flowers. In the hottest parts of the globe, it dies after one flowering, and in arid regions, other species may be more important, but otherwise it is extremely adaptable, and in warm-temperate climates, individual plants may survive for several years. The readiness with which A. majus flower colour and shape mutate and can be crossbred has led to the establishments of unusual (e.g. peloric) cultivars, as well as to making this species one of the first model organisms of genetics and helping uniting the theories of Darwin and Mendel. It remains a key model organism today in fields such as plant developmental genetics. Common toadflax has become established as a model organism more recently; while it may be an invasive nuisance weed in agriculture, like other toadflaxes and snapdragons, its attractive flowers make it useful as a wildflower. At present however, the other members of this family are generally only of minor or localized interest. As the Antirrhineae have long been considered a distinct group, there has also been a long debate about recognition of distinct subdivisions. In 1909, Rouy separated the snapdragon-like subtribe Linarieae from the open-mouthed Anarrhineae and the monotypic Rhodochitoneae, the latter due to their petal-like calyx. By the mid-20th century, Rothmaler on morphological grounds identified five subtribes containing 21 genera: Some 21st-century phylogenetic analyses indicate some quite different lineages. Mainly, the earlier authors seem to have overlumped the snapdragon-like forms (including toadflaxes) which actually do not seem to be closely related, while overemphasizing the morphological diversity of the true snapdragon relatives. As early as 1982, Speta had realized that the typical toadflaxes (including Nuttallanthus) were a lineage well apart from the snapdragons and similar genera, and established the Antirrhininae for the latter. In 2000, combining internal transcribed spacer (ITS) and morphological data from 16 genera, Ghebrehiwet et al confirmed Rothmaler's proposal of a close relationship between the fairly dissimilar-looking Maurandya and Rhodochiton and the distinctness of their lineage from the bulk of the subfamily. However, they found the 'Linarieae' hard to resolve, but could already tell that Kickxia should be moved to the Anarrhinae, and Asarina and Cymbalaria to the Maurandyinae. In addition, Mohavea was recognized as a snapdragon relative with extremely modified flowers, refuting a monotypic Mohaveinae. Vargas et al in 2004 found six probable clades based on ITS and ndhF sequences of 22 genera, which they labelled as: However, they also noted profound morphological diversity amongst the Antirrhinum group, in accordance with the proliferation of segregated genera. Using ITS data from all 29 then-recognized genera, the 2013 study of Fernández-Mazuecos et al. identified six similar clades. They were able to assign all these genera to one of these clades, which they labelled as: