Common names (selected) English: billy goat weed, billgoat-plant, bluebonnet, blue flowered groundsel, bluetop, goatweed, mother brinkley, tropical ageratum, tropical whiteweed, white weed, winter weed; Chinese: 藿香薊 (musk); Hawaiian: maile hohono, maile honohono, maile kula; Hindi (transcribed): Jangli pudina, Visadodi, Semandulu, Gha buti, Bhakumbar; Spanish: celestina azul (Cuba), chuva, flor noble (Guatemala), hierba del perro (El Salvador), hierba de pollo (Honduras), manrubio (Columbia), mentastro (Puerto Rico); yerba de chivo (Dominican Republic) French: azier francois, baume blanc, baume mauve, bouton, bouton blan, bouton ble, eupatoire bleue, herbe a femme, herbe a pisser, herbe a sorcier, herbe de bouc, pain doux, petit pain doux, zerisson blanc; Portguese (Brazil): agerato, camará apeba, camará iapó, camará jape, camara opela, catinga de barao, catingo do bode, erva de Santa Lucia, erva de Santa Maria, erva de Sao Joao, erva de Sao Jose, macela francesa, maria preta, mentrasto, pica roxo; Phillippines: asipukpuk, bahu-bahu, bahug-bahug, budbuda, bulak-manok, kakalding, kamabuag, kolokong-kabanyo, kulong-kogong-babae, singilan

Description: Annual herb

Native range and distribution: Native to South and Central America and the Caribbean, A. conyzoides is a common pantropical weed that can extend into subtropical and temperate zones. The species is now found in Asia, Africa, North America, Europe and Oceania. Its distribution is perhaps more extensive than currently published because the species is also used as an ornamental. 

Urban habitat: A. conyzoides thrives best in rich, moist, mineral soils, and will not grow in the shade. Although preferring a moist habitat, it also grows in dry areas. It is a weed of disturbed land in the Pacific island habitats including crops, pastures, plantations, waste land and roadsides. It is also found in clearings, grasslands, forests, and along trails.

Ecological function: Food and habitat for insects. There is much evidence that A. conyzoides exhibits allelopathic qualities: its root and shoot systems release chemicals that inhibit the growth of nearby plants.

History/human uses: Ageratum comes from the Greek “a”, not, and “geras”, old age, in reference to the flowers lasting for a long time. The plant has a rank smell, likened in Australia to that of a male goat, hence the common name billy goat weed. A. conyzoides is widely utilized in traditional medicine by various cultures worldwide, although applications vary by region. A wide range of chemical compounds including alkaloids, flavonoids, chromenes, benzofurans, and terpenoids have been isolated from this species. Extracts and metabolites from this plant have been found to possess pharmacological and insecticidal activities. A. conyzoides might be a natural herbicide for weed control in rice paddy fields to reduce the dependence on synthetic herbicides. A. conyzoides has been used to treat a diversity of ailments including skin problems, cuts, wounds, burns, pneumonia, stomach ache, malaria, coughs, colds, diarrhea, fever, rheumatism, headache, colic, dyspepsia, eye problems, uterine disorders, and used as a painkiller during childbirth and to treat snakebites. Although A. conyzoides is used as a medicinal plant, it is also reported as toxic, capable of producing liver lesions and tumors. A. conyzoides has been reported as the main reason of a mass poisoning incident in Ethiopia due to grain being contaminated with the species. The species has been attributed magical and superstitious properties by some cultures. The plant’s essential oils are used as a hair wash for treating dandruff.