New Zealand is home to a few carrots with an attitude problem. The most aggressive examples are of course the ferocious ‘Spaniards’ (otherwise known as speargrasses) that were the bane of settlers’ lives in southern parts of the country.
Whilst not nearly in the same anti-social category as its relatives from the genus Aciphylla, our sole native species of sea holly thoroughly deserves the name applied to it by one of my children – ‘prickly bum plant’. The formative experience during which he decided upon this title occurred during a family holiday to the northwestern coast of the Nelson region, where our accommodation just happened to take place on a farm with fine remnants of coastal turf communities.
My interest in New Zealand’s native eryngo (as members of this genus are also known) stems from prior experience with having grown several exotic species of Eryngium within gardens – primarily for their metallic-toned flowerheads. These are frequently blue, as in the case of Eryngium planum or Eryngium amethystinum, and a hint of pale blue-purple is apparent within the relatively small flowers of Eryngium vesiculosum.
This is a large genus (comprising nearly 250 species) with a wide distribution. Eryngo species form basal rosettes of foliage that can be substantial in the case of many South and Central American species – of which several (including E. pandanifolium, E. yuccifolium and E. proteiflorum) are popular within gardens. South and Central America is a centre of diversity for the genus, with around 70% of accepted Eryngium species occurring in South and Central America (including southern states of the USA).
Whether the agent is the salt-laden wind scouring a coastal headland or periodic inundation knocking out the competition on a lake margin, Eryngium vesiculosum finds opportunities in habitats that are kept open by disturbance.
This is true for many groundcovers, but is especially apparent when one observes the conditions in which this small herb thrives. In the coastal turf communities pictured below (in northwest Nelson), Eryngium vesiculosum thrives only in the most exposed positions, along with other significant members of this increasingly rare ecosystem (including Pimelea carnosa, Leptinella calcarea and Wahlenbergia congesta).
The plant shown below owes its tenure to a different form of intervention, as it grows in the dynamic intermediate zone on the margins of Lake Kohangapiripiri. In her book, ‘The Coastal Garden’, Isobel Gabites notes an unusual morphological character that is often associated with seasonal inundation – whereby the leaves of E. vesiculosum change from the wider, toothed leaves borne in summer to narrow, strap-like foliage in winter.