BUR RAGWEED
Ambrosia grayii (A. Nelson) Shinners
DESCRIPTION
Bur ragweed, also known as wooly leaf bursage, is a native, erect, perennial forb, 1-2 feet tall, that reproduces by underground root-stocks and seeds. Stems are usually branching from the base and covered with fine, woolly hairs that give the plant a silvery-gray to purplish-white appearance. The leaves are usually alternate rarely opposite toward the base of the stem), broadly ovate, pinnately 3-5-parted or entire, long-petioled, and dusty greenish-gray. The central lobe of the leaves is usually much larger than the lateral lobes. Male and female flowers are borne in separate heads, with male heads, drooping, about ¼ inch in diameter, and produced in terminal racemes, and female heads, mostly solitary in the leaf axils, 2-flowered, and less than ¼ inch in diameter. The 1-seeded fruits are bur-like, 1/8-1/4-inch-long, and bear stout, straight or hooked spines that are 1/16-1/8 inch long.
Flowering September-frost.
Fruiting September-frost.
PREVENTION OF SPREAD
The Noxious Weed Law (K.S.A. 2-1313a et. seq.) requires all landowners to control the spread of and to eradicate bur ragweed on all lands owned or supervised by them. Methods used for control must prevent both the production of viable seed and destroy the plant’s ability to reproduce by vegetative means. Infestation sites must be monitored after control methods have been accomplished to ensure that dormant seeds in the seedbank do not germinate and establish new infestations.