... of growth.
I know nothing about this plant, which I spotted at Harlow Carr Gardens this morning. I was fascinated by the different stages on display.
I suspect a helpful blipper will be able to tell me more about it, maybe even tell me its name.
Update: After hints and suggestions below, I think I have managed to identify the plant as a Drumstick Allium (Allium sphaerocephalon). Thanks for all your help.