Sea holly, Eryngium variifolium. Spheical head of small, blue flowers surrounded by narrow, spiny, silver bracts.

Sea holly, Eryngium maritimum. Flower heads surrounded by spiny bracts netted with silvery white veins.

Hampton Court Flowershow 2009 'Deserts Delight' garden designed by Jack Dunkley. Dasylirion wheeleri, cropped view of rosette of narrow, spiny edged leaves.