Eryngium ebracteatum var. poterioides

Eryngium ebracteatum var. poterioides is a wild sea holly that is not often found in gardens or nurseries. This perennial and evergreen species is a hardy plant despite its South American origins. It is interesting for its ability to grow in poor and dry soils and for its very long summer to autumn flowering. Its small conical and elongated inflorescences, similar to those of Sanguisorba, are produced abundantly on tall branched stems that emerge from rosettes of long green-grey leaves. It looks stunning when planted en masse, or combined with other wild meadow plants like Rudbeckia, thistles or grasses. Its flowers are also beautiful in fresh or dried wild bouquets.

Eryngium ebracteatum var. poterioides, called 'sea holly with burnet-like flowers' caused a sensation at Plantarium in 2016. However, this sea holly is neither a new horticultural creation nor a hybrid, but a wild perennial of the Apiaceae family native to the Atlantic coasts of Argentina and Paraguay. Its natural habitat consists of savannas. It is a perennial herbaceous plant with evergreen vegetation throughout the year, even in winter. When mature, this Eryngium reaches a height of about 1.20 m (4ft) to 1.40 m (5ft) when flowering, with a spread of 50 cm (20in), depending on the growing conditions.

The foliage is gathered in basal rosettes, composed of linear to lanceolate leaves, 12 to 50 cm (5 to 20in) in length and 0.5 to 3 cm (0 to 1in) in width. They are slightly spiny, sheathing at the base. Their colour is a slightly greyish green.

The flowering occurs from July to September-October. Tall branched stems emerge from the rosettes. Each branch carries at its end a cylindrical inflorescence measuring 1 to 2 cm (0 to 1in) in length and 2 to 4 mm (0.5in) in width. Each inflorescence is composed of tiny dark red to brown flowers surrounded by more silvery bracts.

This Blue Thistle appreciates sun and poor, sandy and rocky, well-drained soils, as close as possible to its natural habitat. It will therefore be ideal in a seaside garden or in a large gravel bed. Very decorative with its beautiful stature and long flowering period, this sea holly will be the perfect companion for plants that thrive in poor soils such as grasses (Stipa, Panicum, Pennisetum, Muhlenbergia), Artemisias, Rudbeckia, drought-tolerant Euphorbias and lavenders, in a very natural or contemporary setting. This thistle with its brown-red flowers is one of the best plants for creating splendid dried bouquets. Simply cut the stems before the flowers fully bloom and dry them upside down.

The roots of this coastal Sea Holly are edible and, after boiling and grilling, have a taste reminiscent of chestnuts. In the United Kingdom, they were used to make sweets.