Baccharis halimifolia

Baccharis halimifolia is a North American species of shrubs in the daisy family. It is native to Nova Scotia, the eastern and southern United States (from Massachusetts south to Florida and west to Texas and Oklahoma), eastern Mexico (Nuevo León, San Luis Potosí, Tamaulipas, Veracruz, Quintana Roo), the Bahamas, and Cuba.
Widely used common names include eastern baccharis, groundsel bush, sea myrtle, and saltbush, with consumption weed, cotton-seed tree, groundsel tree, menguilié, and silverling also used more locally. In most of its range, where no other species of the genus occur, this plant is often simply called baccharis.
Classification.
"Baccharis halimifola" was first described and named by Carl Linnaeus in his "Species Plantarum", published in 1753. No subspecies or varieties are recognized within the species.
This species is the northernmost member of the large Western Hemisphere genus Baccharis in the aster family (Asteraceae).
"Senecio arborescens", a Neotropical species, was confused with "Baccharis halimifolia" in the past.
Description.
"Baccharis halimifolia" is a fall-flowering shrub growing to about 12 ft (4 m) high and comparably wide, or occasionally a small tree. Its simple, alternate, thick, egg-shaped to rhombic leaves mostly have coarse teeth, with the uppermost leaves entire. These fall-flowering "Baccharis" plants are dioecious, with male and female flowers on separate individuals. Their flowers are borne in numerous small, compact heads in large leafy terminal inflorescences, with the snowy-white, cotton-like female flower-heads showy and conspicuous at a distance.
The species is sometimes confused with the marsh-elder ("Iva frutescens"), with which it often co-occurs, but the "Baccharis" has its leaves alternate, while those of the "Iva" are opposite.
Ecology.
"Baccharis halimifolia", usually found in wetlands, is unusually salt-tolerant, and often found along salty or brackish shores of marshes and estuaries, and the inland shores of coastal barrier islands. In Florida, it is also found along ditches, in old fields, and in other disturbed areas. Other habitats in the northeastern United States include freshwater tidal marshes and open woods and thickets along the seacoast.
The flowers produce abundant nectar that attracts various butterflies, including the monarch ("Danaus plexippus"). These dense shrubs also provide wildlife food and cover.
Invasiveness.
In Australia, "B. halimifolia" is an invasive species along the coast of southern Queensland and New South Wales. As biological control the rust fungus "Puccinia evadens" is used.
The species has also become naturalized in Europe and in New Zealand.
In the northeastern United States, the species has become common well inland of the shrub's natural range along various major highways where road salt is heavily used, sometimes forming conspicuous displays when flowering in the fall, as along I-95 in Howard County, Maryland.
Toxicity.
The seeds of "Baccharis halimifolia" are toxic to humans.
Uses.
"Baccharis halimifolia" is occasionally cultivated, useful as a hedge or border as well as a specimen plant.
In southern Louisiana, it has been traditionally used as a medicine to treat inflamed kidneys and fever.