Northern Ireland's Priority Species

Silene gallica – small-flowered catchfly

 

Distribution map

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Silene gallica L.
Family: Caryophyllaceae

A small, rough-hairy winter annual (three varieties recognised), introduced, very rare and declining. It is a casual alien weed of lowland, sandy or nutrient-poor, cereals and other arable fields, also found in disturbed wayside and coastal sites. Flowers June to October, usually with dingy white or yellowish (var. anglica) or occasionally pink (var. sylvestris), slightly notched petals.
Traditionally, and until very recently (e.g., Stace 1997), this weedy annual was considered native in Britain and 'probably introduced' in Ireland (Scannell & Synnott 1987). Reassessed, it is now recognised as an ancient introduction by man (pre-1,500 AD), i.e, it is an archaeophyte.

In brief

  • It flowers in spring and early summer in dry, open places, sandy and gravelly ground on lowland arable fields, roadsides, edges of paths and on waste ground
  • It can also occur in drought-prone coastal grassland and cliffs
  • Sometimes the sticky hairs do catch tiny insects as the English Common Name suggests, but they are not involved in the nutrition of the plant
  • Possessing a taproot, the plant is quite drought-tolerant and it competes successfully for moisture with native species in many relatively dry soil situations, such as around puddles, temporary pools and seeps
  • Seedlings are sensitive to low winter temperatures, failing to survive at temperatures of - 10C (Stewart et al. 1994)

Species description
Annual 1040 cm tall, stem branched, erect, occasionally sprawling, minutely bristly. The upper parts of the plant are covered with sticky glandular hairs. Leaves are opposite, oblong, reducing in size upwards; lower 13.5 cm; upper 0.82.5 cm, more or less covered with glandular hairs, and narrowing to an abrupt tip or mucro. The base of the plant becomes woody as it ages. Flowers small, 6-9 mm in diameter, well-spaced, stalkless or short-stalked in a one-sided flowering branch (inflorescence) with leafy bracts (modified leaves) bearing 5-10 blossoms. Calyx 710 mm long, glandular-hairy, inflated in fruit, with 8 green or purplish veins. Petals slightly notched or unnotched, white or pink, very rarely with dark crimson blotch on base of limb. Fruit an ovoid capsule up to 1 cm long. Seed numerous, kidney-shaped, wrinkled, dark red or brown, up to 1 mm long.

Life cycle
Seeds germinate either in autumn (winter annual) or early spring. While it is moderately competitive, the species tends to avoid other plants, frequenting open, somewhat disturbed, sandy or gravelly soils in wayside situations: sometimes coastal, or beside temporary water, or along trails by rivers, streams, roads and paths. Flowers are produced from spring to early summer. Populations can become locally abundant if there is little competition. Seed is generally dispersed near the parent plant, but grazing and other forms of disturbance by man can help transport it further afield. When buried in the soil the seed is transient (less than one year), or short-term persistent (surviving 1 to 5 years)(Thompson et al. 1997).

Similar species
None found in Northern Ireland.

How to see this species
Small-flowered catchfly is an extremely rare, casual weed in Northern Ireland. It may quite sensibly be considered locally extinct. The NI Flora Database at CEDaR (see below) contains just 8 sightings for S. gallica, 3 of them from the 20th century, but only one within the last 20 years. Reynolds (2002) listed a total of just 4 post-1987 records for the whole of Ireland.

Current status
The introduced archaeophyte weed has only ever very rarely been observed in Ireland. It appears to be declining in many countries, especially in more northern parts of Europe. By 1930 it had been lost from many inland sites in Britain and Ireland (Perring & Walters 1976), and the decline has continued to the present day.

Why is this species a priority in Northern Ireland?
Small-flowered catchfly 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 of 2006 ranks Silene gallica as endangered, having suffered a population size reduction equal or over 80% during the last 10 years.

Threats/Causes of decline
Since decline began pre-1930 and has continued for over 80 years, it very probably emanates from more than one cause. Population losses have been especially noticed since the introduction of modern intensive agriculture practices, including seed cleaning and the development and widespread use of chemical fertilisers and selective herbicides (Preston, Pearman & Dines 2002). However, since initial decline began in inland sites, and has gradually spread southwards in Britain, a climatic factor may also be involved. Global warming associated with increased levels of atmospheric carbon dioxide appears to have increased the frequency of harsh winter weather conditions in the northwestern Atlantic region, a circumstance likely to reduce the probability of sensitive seedlings successfully overwintering.

Conservation of this species

Current action
The plant is listed as a Northern Ireland Priority Species.

Proposed objectives/actions
Local field botanists are encouraged to look out for the species and report any finds. The status of Small-flowered catchfly 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. Telephone: 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
Perring, F.H. and Walters, S.M. (eds.)(1976). Atlas of the British Flora. 2nd edition. Botanical Society of the British Isles, EP Publishing Ltd, Wakefield, England.
Preston, C.D., Pearman, D.A. and Dines, T.D., eds (2002). New atlas of the British and Irish flora. Oxford University Press, Oxford.
Reynolds, S.C.P. (2002). A catalogue of alien plants in Ireland. Occasional Papers, No. 14. National Botanic Gardens, Glasnevin, Dublin.
Scannell, M.J.P. and Synnott, D.M. (1987). Census Catalogue of the Flora of Ireland, 2nd edition, The Stationery Office, Dublin.
Stace, C. (1997). New Flora of the British Isles, 2nd edition. Cambridge University Press, Cambridge.
Stewart, A., Pearman, D.A. and Preston, C.D. (1994). Scarce plants in Britain. Joint Nature Conservation Committee, Peterborough.
Thompson, K., Bakker, J.P. and Bekker, R.M. (1997). The soil seed banks of north west Europe. Cambridge University Press, Cambridge.

Text written by:
Ralph Forbes