What Is This Garden Plant?

The attached image is a plant that is all over our back yard. I have had two severe allergic reactions while weedeating it. We did not realize the first time it happen that the plant was the cause. I was told it may be some type of philodendron, but I cannot find an image that looks like it. There are no thorns and no blooms. When cut, it has an odor that will burn the nose and throat. Please help.