Cow parsnip can often be confused with giant hogweed, so I think it's important to make sure we have identified the plant correctly. You didn't send any pictures of the foliage or stems, so it's difficult to tell, but it did look in the images like the seeds may be heart shaped, which would mean that it is cow parsnip. Below is a link to a document that shows the attributes of both giant hogweed and cow parsnip to help you correctly identify your plant. Please contact me again if you have any issues with identification or if the plant indeed has the characteristics of giant hogweed at firstname.lastname@example.org.
Thank you for using Ask an Expert!