the seeds of cocklebur

annual axils branching bur burr central clotbur clothing cocklebur colonies common compound daisy develop donkey donkeybur dye family female flowers formed fruit fruits fur hair heartleaf hitchhikes inspired invention leads leaf lower male minimal monoecious occurs organs plant pollination prickly produces raceme racemes reproduction reproductive rough seeds self-seeding short spike-like stem stems strumarium summer upper velcro weed wind woolgarie xanthium yellow