Xanthium spinosumXanthium spinosumTaxonomy
Xanthium spinosum L., Sp. pl. 2:987. 1753Common synonyms
Acanthoxanthium ambrosioides (Hook. & Arn.) D.Löve; Acanthoxanthium spinosum (L.) Fourr.; Acanthoxanthium spinosum subsp. catharticum (Kunth) D.Löve; Acanthoxanthium spinosum subsp. spinosum; Xanthium ambrosioides Hook. & Arn.; Xanthium armatum Humb. & Bonpl.; Xanthium armatum Humb. & Bonpl. ex Wallr.; Xanthium canescens (Costa) Widder; Xanthium catharticum Kunth; Xanthium medium Nossotovsky; Xanthium multifidum Larrañaga; Xanthium spinosum f. inerme (Bel) O.Bolòs & Vigo; Xanthium spinosum f. laciniatum Scheuerm. & Thell.; Xanthium spinosum f. laciniatum Scheuerm. & Thell. ex Widder; Xanthium spinosum f. praecocius Bitter; Xanthium spinosum f. praecocius Bitter ex Widder; Xanthium spinosum f. spinosum; Xanthium spinosum var. ambrosioides (Hook. & Arn.) Love & Dans.; Xanthium spinosum var. brachyacanthum DC.; Xanthium spinosum var. canescens Costa; Xanthium spinosum var. heterocephalum Widder; Xanthium spinosum var. inerme Bel; Xanthium spinosum var. synacanthum Widder; Xanthium xanthocarpon Wallr.Common name
Bathurst burr.
Description
Propagule or dispersal unit is the whole female fruiting head, which is developed as a burr. Fertile part (6-)9-12(-13) mm long, 3.5-5.5 mm wide, in side view widest in upper part (obovoid) or widest in the middle, +/- straight, the upper (apical) end narrowing, in cross-section round, basal scar (carpopodium) inconspicuous and undifferentiated, central, beak (=thinner sterile stalk between seed and pappus) absent, wings absent, propagule surface light brown or straw, prickly, with woolly / crispate hairs or glands or glandular hairs, thickened margin absent, longitudinal ribs absent.
Pappus absent.
Note: The weedy genus Xanthium has several species that are sometimes hard to differentiate.
Ecology
Annual herb; the propagule is the entire female flowering head ("conceptacle") which is developed into a burr sticking to fur and clothes. Temperate to tropical regions. Found in a variety of disturbed areas including croplands, but particularly problematic on sheep pastures, as the burrs contaminate the wool.
Native range
Presumed to be South America.
Introduced range
United States, Mexico, (Ecuador, Peru, Bolivia, Chile, Brazil, Argentina, Paraguay, Uruguay,) most of Europe, Mocorro, Israel, Ethiopia, Zimbabwe, South Africa, Australia, New Zealand.
