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clotbur,any species of the genus Xanthium, widely distributed, coarse annual plants of the family Asteraceae (asteraster
[Gr.,=star], common name for the Asteraceae (Compositae), the aster family, in North America, name for plants of the genus Aster, sometimes called wild asters, and for a related plant more correctly called China aster (Callistephus chinensis
..... Click the link for more information. family). They are often persistent weeds; the two-seeded oval burrs are particularly troublesome to sheep growers and the very young plants are poisonous to livestock. Cockleburs are often confused with burdock. Cockleburs are classified in the division MagnoliophytaMagnoliophyta
, division of the plant kingdom consisting of those organisms commonly called the flowering plants, or angiosperms. The angiosperms have leaves, stems, and roots, and vascular, or conducting, tissue (xylem and phloem).
..... Click the link for more information. , class Magnoliopsida, order Asterales, family Asteraceae.
plant of the genus Xanthium; annual grasses of the Compositae family. The flowers are tubular and unisexual and are formed in unisexual calathide heads. The staminal calathides are multiflorous, round, and apical; the pistil calathides each have two blossoms; both develop on a single plant. Estimates of the number of species range from just a few to 25, and they are found all over the world. There are seven species in the USSR. The most widely found is burweed (X. strumarium), which grows as a weed on vacant land, on cultivated land, and in gardens, along roads, and near houses. Thorny cocklebur (X. spinosum), which has long two- or three-segment spikes at the base of its leaves, is found in the southern regions of the USSR (in refuse areas, along roads, and in pastures).
T. V. EGOROVA