Laennecia or Laënnecia is a genus of flowering plants in the family Asteraceae. The plants are native to Mesoamerica, South America, and the southwestern United States. Common name is "horseweed."SpeciesLaennecia altoandina (Cabrera) G.L.Nesom - Jujuy in Argentina, La Paz in Bolivia, Cusco in Peru Laennecia araneosa (Urb.) G.Sancho & Pruski - Dominican Republic Laennecia artemisiifolia (Meyen & Walp.) G.L.Nesom Laennecia chihuahuana G.L.Nesom - Chihuahua Laennecia confusa (Cronquist) G.L.Nesom - Chiapas, Guatemala, Costa Rica Laennecia coulteri (A.Gray) G.L.Nesom - Mexico, United States Laennecia eriophylla (A.Gray) G.L.Nesom - Arizona Laennecia filaginoides DC. - Central America, Colombia, Ecuador, Venezuela, Mexico, Texas Laennecia gnaphalioides (Kunth) Cass. - Chiapas, Oaxaca, Central America, Colombia, Ecuador, Peru, Bolivia, Venezuela Laennecia microglossa (S.F.Blake) G.L.Nesom - Nuevo León Laennecia pimana G.L.Nesom & Laferr. - Chihuahua Laennecia schiedeana (Less.) G.L.Nesom - Central America, Mexico, USA Laennecia sophiifolia (Kunth) G.L.Nesom - South America, Mesoamerica, USA Laennecia spellenbergii G.L.Nesom - Durango Laennecia turnerorum G.L.Nesom - Texas