It is one of the main pathogens of human pollinosis. Occupy farmland, resulting in reduced crop production. Being eaten by cows leads to the decline of milk quality. It can inhibit and repel Gramineae and Compositae plants.

Ragweed (scientific name: ragweed. ): panicum miliaceum, height 20-150 cm; The stem is erect, with conical branches in the upper part, angular and rough.

Lower leaves are opposite, petiole is short, secondary pinnate division, lobes are narrow, oblong to oblanceolate, entire. The upper part is dark green, short or nearly hairless, the latter part is grayish green, and the dense quilt is short and thick. Male cones are hemispherical or ovoid, with a diameter of 4-5 mm, short peduncle, drooping and dense branches into racemes.

Hemispherical or discoid with wide involucre; Corolla pale yellow, 2 mm long, short tube, bell-shaped upper part, wide lobes. Achenes obovate, glabrous, hidden in a hard involucre. The flowering period is August-September, and the fruiting period is 9-65438+1October.