Thursday, September 17, 2009
This plant has male and female flower heads. The female heads are the burs and each bur has two seeds inside it. One of those seeds will germinate the following year and the second seed will remain dormant until the second year or even later. The thick yellow sap from this plant has been used as a hair dye. It is poisonous to animals and the burs will clump together in the stomach and intestines. The great virtue of cocklebur is that it led to the invention of Velcro. A Swiss engineer upon finding cocklebur stuck to his pant leg put the burs under a microscope and then found a way to weave nylon so that the hooks on one side grabbed the loops on the other side.