I'm short, so this plant is T A L L!
Rob Proctor mentioned in his blog this was the plant he had the most questions about during the tour. They were throughout the garden in all sizes and stages of flowering.
They're called giant cow parsnip.
An interesting bud!! About my eye level, I think.
There were about 6 brick columns on each side of a grass pathway with perennials on both sides of the "fence". Close to five feet tall.