Eryngium Agavifolium

A few years ago I obtained seeds of this plant from the RHS. They have a seed bank at Kew and distribute seeds on request to their members. It was an interesting exercise and this Eryngium Agavifolium (also known as agave leaved sea holly) was one of the most successful germinations. I put the plants in various spots around the garden to let them mature. They haven't yet flowered or reached their max height of up to 2 metres. Wish I'd read the description mire carefully. :(