We have a friend who works for the USDA seed bank in Ames, preserving many varieties of seeds. One of the latest plants to be grown out for fresh seed was a variety of Hungarian parsley.
photo credit: ISU News Service.
This plant grew to be about 7 feet 10 inches tall. The whole story can be found on an ISU news page. The plant is in the process of being certified by the Guinness Book of World Records as it beat the old record by nearly 2 feet!
Now if you ever have to roast a whole cow and need a garnish, is the parsley for you to grow!