Transverse section of the petiole, or leaf stalk, of Heracleum sphondylium, commonly known as hogweed, common hogweed or cow parsnip. Hogweed belongs to the same family as parsley and carrots (Apiaceae) also known as umbellifers because of the umbrella-like appearance of the flower heads. Numerous vascular bundles are distributed throughout the petiole. Magnification: x14 at 10cm wide.