Northern Ireland's Priority Species

Salsola kali subsp. Kali – prickly saltwort

 

Distribution map

Click here to view an interactive map of the Northern Ireland dataset as currently collated by CEDaR.
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Salsola kali subsp. Kali L.
Family: Chenopodiaceae

A native annual plant that grows, usually more or less prostrate, in sandy coastal soils just above the drift-line on the foreshore or at the base of foredunes: much rarer on sand/shingle mixtures. It is widespread but local, and presence varies from scarce to locally abundant around the mid-latitude coasts of Great Britain. However, in recent decades it has declined and become increasingly rare, especially along the English Channel coast in areas where public pressure is greatest. On Irish coasts the plant is intermittently frequent, sometimes locally abundant, along the Irish Sea between counties Down and Waterford: elsewhere it is thinly scattered and occasional on western shores from Kerry to Donegal.

In brief

  • The plant tolerates maritime conditions and its tissues are succulent, i.e. they store water (and the water is salty). Such plants are called halophytes (from Greek meaning 'salt-tolerant plants')
  • The tip of each linear leaf of the mature plant is armed with a rigid woody spine up to 2 mm long, hence the English Common Name
  • In the past, when the plant was burnt, the sodium in the salt ended up in the chemical sodium carbonate, or ‘soda’, which was used to make glass and soap
  • Inconspicuous, stalkless flowers each with a whitish or membranous perianth consisting of 5 segments (tepals) are produced in July and August. They are surrounded by 2 or 3 short modified leaves or bracts which are also spiny
  • In Northern Ireland, nowadays it is confined to a few sites on the County Down coast

Species description
Summer annual, very variable (several named forms exist). Plant greyish-green. Stem usually spreading and prostrate, rarely erect and bushy, up to 60 cm, sometimes striped red, richly branched from the base. Leaves spreading, succulent, round or half-round in section, linear, 1-4 cm long, apex with a 1-2 mm spine. Flowers 3.5 mm in diameter, inconspicuous, solitary in the angle between leaf base and stem, each surrounded by 5 small, pale or membraneous, leaf-like bracts (tepals) which are also spine-tipped. In fruit the tepals surround a somewhat flattened round nut, and they become whitish and winged.

Life cycle
A 'therophyte' or summer annual, seeds germinate in the spring, when winter rain has washed out some of the salt from the soil, and the nut and covering protective bracts have weathered sufficiently to allow water to penetrate. Establishment typically occurs around seaweed wrack on the driftline of exposed sandy beaches. Occasionally plants occur further up the shore in open areas of mobile marram dunes. Populations vary greatly in abundance from year to year depending upon levels and timing of disturbance from weather and/or human or other animal activity. Populations can become locally abundant if there is little competition from other plants. The species can withstand periodic immersion in sea-water. After flowering the plant dies, but on drying it hardens and often remains on the shore all winter. The fresh plant contains oxalates that are toxic and dangerous to grazing sheep or cattle. In the past it was regarded as medicinal: juice of the fresh plant was considered an excellent diuretic.

Similar species
None when in flower, or in its characteristic habitat.

How to see this species
Prickly Saltwort is very characteristic of the foreshore of sandy beaches. In Northern Ireland it is readily found in suitable coastal sites (e.g. Killard, Co. Down), but it is also locally frequent and quite widely recorded on sandy beaches in the Republic of Ireland, especially from Dundalk to Dungarvin, but also on the west coast as far north as Co. Donegal.

Current status
In Britain this annual began to decline prior to 1930, losses at first, apparently, being confined to the northern half of the island (Perring & Walters 1976). A similar pattern of population loss took place around northern coasts in Ireland, and by 1999 the New Atlas map showed a loss of 49% of all previously recorded sites in Britain and Ireland, and an Atlas Change Index of -0.61 has been calculated.

Why is this species a priority in Northern Ireland?
Prickly Saltwort is listed as a Priority Species of Conservation Concern in Northern Ireland on account of its being listed as UK Priority Species (Species of Principal Importance in both England and Wales), which has suffered a major decline. The Great Britain Red Data list ranks Salsola kali as vulnerable, having suffered a population size reduction equal or over 30% during the last 10 years. The NI Plant Species Database at CEDaR contains records from around 23 sites (some poorly located), only 9 of which have records that post-date 1975.

Threats/Causes of decline
Since decline began pre-1930 and has continued for at least 80 years, it very probably emanates from more than one cause. However, since initial decline began in northern regions and has gradually spread southwards, a climatic factor may also be involved. Global warming associated with increased levels of atmospheric carbon dioxide appears to have increased the frequency and severity of storms in the North Atlantic, a circumstance which would certainly reduce the probability of seedling establishment success on exposed sandy beaches.

Conservation of this species

Current action
The plant is listed as a Northern Ireland Priority. The known sites are monitored on an ad hoc basis by field botanists.

Proposed objectives/actions
The status of Prickly Saltwort will be surveyed and monitored and appropriate conservation action undertaken if required.

What you can do
You can assist by helping to monitor the health and size of populations. Any sites additional to those currently known would be of great interest. All records should be reported to either the Botanical Society of the British Isles (BSBI) or to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, Co. Down, BT18 0EU. Tel: 028 9039 5264, email: cedar.info@nmni.com

Further information

Links
BSBI map

Atlas of British & Irish Flora

Irish Wild Flowers

The Vascular Plant Red Data List for Great Britain - 2005

Literature
Grieve, M. (1931 and many reprints). A modern herbal. Jonathan Cape, London, Toronto and New York.

Text written by:
Ralph Forbes