Xanthium spinosum (syns. Acanthoxanthium spinosum )
The plant is a well armored summer annual growing 3-4 feet tall. The leaves covered with short white hairs, white-veined above, 1 to 3 inches long and have 2 short lobes and a 3-forked spine at the junction with the stem. Male flowers are segregated from the female by being located in the uppermost parts of the plant and clustered. Female flowers are below male flowers and form a beaked bur that bears many small hooked bristles.
Height of mature plants
July through October
Spiny cocklebur is most frequently found in highly disturbed waste areas and barnyards. It surrounds many small reservoirs in Oregon.
The burs of spiny cocklebur can become tangled in the hide or wool of livestock adding to the cost of the woolen product. It is moderately competitive and is a nuisance in hand-harvested crops. The seeds and seedlings of spiny cocklebur are poisonous. The symptoms are anorexia, depression, nausea, and prostration. Death may occur in a few hours to three days after the symptoms are first noted.
Noxious Weed Listing: