Several species of "Ageratum" are toxic, containing pyrrolizidine alkaloids. Tall ageratum are also available in seed catalogues. The ordinary Ageratum is a perennial, herbaceous plant or a dwarf, or shrub. "Ageratum houstonianum" and "Ageratum conyzoides" cause liver lesions and are tumorigenic. "Ageratum houstonianum" is toxic to grazing animals, causing liver lesions. Common herbs are "Ageratum adenophorum", "Maesa indica" and "Eurya cerasifolia". "Ageratum" are prone to becoming rampant environmental weeds when grown outside of their natural range.