Monument Plant - Giant Gentian
Frasera speciosa (Swertia radiata)
This plant is an impressive thing to see en masse. For a green and white flower, there are gorgeous close-up details you have to see to believe. The summer of 2105, in northern Colorado, I saw mountainsides of this thing in all it's glory. A great beauty.
Green Gentian is a monocarpic perennial and will bloom when it's darn good and ready. It can bloom only once in 20-80 years. Until then, it will be a beautiful strappy-leafed rosette for decades until it decides to shoot up a glorious flower stalk. This plant can also have a mass blooming, how they know - no one knows - as some plants will sit and wait.