Barkleyanthus is a monotypic genus of flowering plants in the aster family, Asteraceae, containing a single species, Barkleyanthus salicifolius. The genus was segregated from the large and historically catch-all genus Senecio, to which its sole species was previously assigned.
The plant is a shrub that typically grows one to two metres tall, though specimens exceeding four metres have been recorded. Its stems are branching, and the leaves are roughly lance-shaped (willow-like in outline), alternately arranged along the stems, and up to 10–15 centimetres long. The inflorescence is typically a broad, open array of several flower heads. Each head bears a few yellow ray florets, which are pistillate, and up to 25 or more yellow disc florets, which are bisexual. The fruit is a rough-textured, pyramidal cypsela topped with a pappus of many barbed white bristles for wind dispersal.
Barkleyanthus is native to North and Central America, ranging from the southwestern United States south through Mexico to El Salvador. It is particularly abundant in Mexico, where it can become weedy. The plant flowers year-round, with peak flowering in spring. Its bright yellow flower heads have made it popular as an ornamental. In Mexican traditional medicine it is used to treat fever and rheumatism, and in the state of Chiapas it is used as a grain insecticide to protect corn supplies.
Etymology
The genus name Barkleyanthus honours Fred Alexander Barkley, an American botanist who worked extensively on Compositae taxonomy (reflected in the common name "Barkley's-ragwort"). The specific epithet salicifolius derives from Latin salix (willow) and folium (leaf), describing the lance-shaped, willow-like leaves — hence the common names willow ragwort and willow groundsel.
Distribution
Barkleyanthus salicifolius is native to North and Central America, with its range extending from the southwestern United States southward through Mexico — where it is most abundant — to El Salvador. It is particularly prevalent at mid-elevations in Mexico and can become locally weedy.
Ecology
The plant flowers year-round, with peak bloom in spring, and may be in full flower at the end of the dry season. It is abundant in parts of its range, particularly in Mexico, and can behave as a ruderal or weedy species in disturbed habitats.
Cultural Uses
In Mexican traditional medicine, Barkleyanthus salicifolius is used to treat fever and rheumatism. In Chiapas, the plant is used as an insecticide to protect stored corn. Its showy yellow flower heads have also led to its cultivation as an ornamental shrub.
Taxonomy Notes
Barkleyanthus was segregated from the large, polyphyletic genus Senecio (tribe Senecioneae, family Asteraceae). Its sole species was formerly known as Senecio salignus. Secondary metabolites characteristic of the genus include pyrrolizidine alkaloids, lactones, furoeremophilanes, and sesquiterpenes.
