Baccharis/ˈbækərɪs/[3] is a genus of perennials and shrubs in the aster family (Asteraceae). They are commonly known as baccharises but sometimes referred to as "brooms", because many members have small thin leaves resembling the true brooms. They are not at all related to these however, but belong to an entirely different lineage of eudicots. B. halimifolia is commonly known as "groundsel bush", however true groundsels are found in the genus Senecio.
Baccharis, with over 500 species, is one of the largest genera in the Asteraceae.
It is found throughout the Americas, distributed mainly in the warmer regions of Brazil, Argentina, Colombia, Chile and Mexico,[4] with B. halimifolia ranging northward along the Atlantic Coast to the southern tip of Nova Scotia in Canada.[5]
If present, the leaves of Baccharis are borne along the stems in alternate fashion. Flowers are usually white or pinkish. There are no ray flowers, but many disk flowers which are either staminate or pistillate.
Some species of Baccharis are toxic to animals; in particular, consumption of B. coridifolia may lead to necrosis in the gastrointestinal tract of cattle, horses, sheep, and rabbits.
Baccharis conferta, native to Mexico, was chosen to serve as nurse plants to protect from frost and drought newly planted tree seedlings of Abies religiosa in the world's first assisted migration experiment that coupled upslope planting of the fir tree in anticipation of climate change forcing overwintering Monarch butterflies to seek higher elevations in central Mexico.[8]
Uses
Several species of Baccharis are of interest for cultivation, as the dense but flexible stem structure makes for a good windbreak.
Plants of this genus are rich in terpenes, and some are used in native or folk medicine. One that has been specifically described from Chilean and Argentinean Baccharis is viscidone.
Baccharis flowers are rich in nectar, and several species are good honey plants. Particularly B. dracunculifolia is highly esteemed by beekeepers.
Conservation
A few Baccharis species (especially from the northern Andes) are almost extinct due to habitat destruction. The northernmost occurrence of B. halimifolia, in Nova Scotia, Canada, is also receiving conservation attention.[5]
