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."

Species

• Laennecia 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 (Coahuila, Nuevo León, Sonora), United States (CA NV AZ UT CO NM TX AL)
• Laennecia eriophylla (A.Gray) G.L.Nesom - Arizona (Pima, Santa Cruz, Cochise Counties)
• 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 (AZ CO NM)
• Laennecia sophiifolia (Kunth) G.L.Nesom - South America, Mesoamerica, USA (AZ TX NM)
• Laennecia spellenbergii G.L.Nesom - Durango
• Laennecia turnerorum G.L.Nesom - Texas (Brewster County)

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