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Taiwan Invasive Species Database | Family List | Asteraceae

Chromolaena odorata (L.) R. M. King & H. Rob., Phytologia. 20(3): 204. 1970; Peng & Yang, Taiwania 43(4): 261, fig. 1. 1998.


Chromolaena odorata

  • Eupatorium odoratum L.

    life form: herb, plant

    description: Perennial coarse herbs to 2 m tall; stems terete, striate, crisp-puberulous. Leaves opposite, median ones larger, ovate to subdelotoid, 7-15×3.5-8 cm, apex acute to acuminate, base obtuse to very broadly cuneate or truncate, sometimes decurrent, lower surface glandular punctate, 3-nerved, margins sparsely dentate, sometimes entire apically, petiole 1-2.5 cm long; upper leaves gradually smaller near inflorescence. Inflorescence loose corymbs, heads ca. 10 mm long, 4.5-5 mm wide, peduncle 8-16 mm long, densely pubescent; involucre cylindric, ca. 7 mm long; bracts ca. 30, 3-4 seriate, trinerved, outer ones ovate to ovate oblong, inner ones narrowly oblong, apex acute, base obtuse, sparsely pubescent. Florets ca. 30. Achenes black, ca. 4-4.5 mm long, 5-angular, pubescent on ribs.

    origin: Native of tropical America

    Summary: A fast-growing perennial herbs native to South America and Central America. It has been introduced and has become an aggressive invasive weed in much of tropical Asia, Africa, and the Pacific. Siam weed forms dense stands, which prevent establishment of other species, both due to competition and allelopathic effects. It is also a problem in agricultural land and commercial plantations.

    Habitat: agricultural areas, disturbed areas

    status: alien

    occurance: established and expanding

    invasiveness: invasive

    introduction types: intentional

    pathways of introduction types: by agricultural interests, introduced for medicinal purposes

    vector of introduction types: anthropogenic vectors

    impact types: competition, economic, environmental

    eradication methods: poison, mechanical


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