Xanthium strumarium aka California Bur

Xanthium strumarium, also known as rough cocklebur, clotbur, common cocklebur, large cocklebur, or woolgarie bur, is a species of annual plants in the family Asteraceae. Its origins are uncertain, with some sources claiming it originates in southern Europe and Asia, while others state it originates in the Americas but was introduced to Eurasia early on. Xanthium is a genus of flowering plants within the daisy family and is native to eastern Asia and America. The plant is much-branched and can grow up to 150 cm high, with erect stems that are stout, green, brownish or reddish-brown, and roughly hairy. The seeds of these plants are covered with stiff and hooked spines that attach to the fur of animals, making them a potential contaminant. However, they are also a source of bee forage. It is important to note that cocklebur might be poisonous. The most effective methods of cocklebur control are hand pulling or chemical controls as they reproduce easily by seed, which can remain dormant in the soil for up to three years before germinating under ideal conditions. Cocklebur is a summer annual weed that grows 2-4 feet tall and prefers moist to wet sandy loam or loams in full sun to partial shade. They have minimal branching, except for short side stems that develop from the leaf axils.