This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
This is a fine European Sea Holly, 2-3 ft. high, having spiny lobed leaves, and bright-blue or amethyst-purple flowers and bracts. Closely related is E. Oliverianum, a taller plant with amethyst-blue flower heads. Other less-attractive species are alpinum, 3 ft., pale blue; Bour-gati, 1 ft., small, blue; giganteum, 3-4 ft., glistening white (should be treated as a biennial); ma-ritimum, 1-2 ft., the common British Sea Holly with grey-green leaves and bracts; and planum, small blue. Such species as agavoefolium, bromelioe-folium, eburneum, and pan-danaifolium (fig. 197) have long strap - shaped spiny leaves in rosettes, with the flower heads standing well above them. All species are easily raised from seeds, but the plants may vary a good deal in colour. Root cuttings and careful division may be practised in spring for particularly fine varieties to keep them true. In a cut state the plants last a long time, and are used as "everlastings".
Fig. 197. - Eryngium pandanifolium.