Trollius europaeus – globe-flower
Trollius europaeus L.
Family: Ranunculaceae
This handsome perennial, which looks rather like a robust buttercup but with the flowers more globular and compacted, has declined over the last century and now occurs in Ireland in one very specialized habitat only — the narrow zone about two or three metres wide around the winter high watermark on rocky lake shores under the shade of alder, willow and rose scrub. The species appears to have been declining in range over a long period, perhaps for a century or more, particularly at the margins of its previous European distribution. Essentially a Northern-temperate species, it becomes more of a mountain plant in its southern areas of occurrence.
In brief
- Elsewhere in Britain Trollius europaeus is a decidedly northern species, being much more common in Scotland and Cumbria than further south, although it does occur in North Wales
- This species is found in Fermanagh on the shores of Lough Melvin, plus in a couple of sites on Upper Lough Macnean
- A perennial of cool, damp, fully-illuminated or semi-shaded situations, it prefers base-rich soils and is generally associated with limestone districts
- The plant is recognisable throughout the year
- It is an Irish Red Data Book species, classed as vulnerable
- It is sensitive to grazing pressure, particularly sheep and goats, and is often restricted to inaccessible, ungrazed sites either protected by wire, on lake islands, or in other areas of its distribution on moist rock ledges, steep river banks or in gullies.
Species description
The large basal palm-like, deeply-cut leaves are perfectly recognisable in winter. As the English common name suggests, the lemon-yellow flower, 20 to 45cm in diameter, is almost spherical, unlike any other. It remains closed, like a large yellow bud at the top of long, 50cm tall flower stems. Pollination is achieved by small flies that take up residence inside the flower (Fitter et al., 1996).
Life cycle
Trollius produces a short, erect, fibrous rootstock and has no powers of vegetative reproduction. It relies on seed production for both increase and species dispersal. It flowers in May and June, and seeds ripen from July to September. Like other members of the buttercup family (the Ranunculaceae) globe-flower contains the blister-inducing, bitter-tasting poison ‘protoanemonin’, to deter browsers and protect the plant (Cooper and Johnson, 1998). Large herbivores are known to graze the plant and seeds are transported internally, appearing in dung (Ridley, 1930). Thus the toxin levels in Trollius may not deter cattle, sheep and goats and they may assist with seed dispersal. Further study is required to investigate this possibility.
Similar species
No other ‘buttercup’ has flowers as large, with more than five ‘petals’ and leaves so deeply divided into three to five toothed segments.
How to see this species
On Lough Melvin it still occurs in abundance on Gorminish Island and has been found sparingly on Bilberry Island. Previously, it was at Rosskit but has not been refound there recently. On Upper Lough Macnean, it still occurs sparingly on Rushin Point over less than 100 metres of the shoreline, and a few plants have been found to the west, on the mainland opposite Kilrooscagh Island. The main station for the plant on this lake appears to be on the Cavan shore where it was discovered in the 1990s. It is easiest to find when flowering in May and June. There is no public access to the shores of either of these lakes, which are part of private farmland. Lough Melvin is an ASSI. Relevant access permissions should always be sought prior to visiting any sites.
Current status
The globe-flower grows in Fermanagh on the shores of Lough Melvin, and in a couple of sites on Upper Lough Macnean; wells on the County Cavan side of the lake. Apart from these, the only other Irish stations are two or three places in County Donegal, although it also use to grow in County Leitrim. All wild plants are given some measure of protection under the Wildlife (NI) Order, 1985. Fifty-six species, including Trollius europaeus are listed in Schedule 8, parts 1 and 2, and given special protection.
Why is this species a priority in Northern Ireland?
- It is rare with Northern Ireland being the stronghold for the Irish population
- It is an Irish Red Data Book species, classed as vulnerable.
Threats/Causes of decline
The main causes of Trollius decline in Britain and Ireland appear to be agricultural improvement of land through drainage (especially in hilly areas), plus earlier and more frequent cutting of meadows for silage than previously for hay. The widespread application of fertiliser also encourages the growth of more vigorous competitors which globe-flower simply cannot withstand. Populations near river and stream banks have been destroyed in Donegal by flash floods, a weather-related phenomenon increasing in frequency which may be related to global climate change. On Bilberry Island, grazing by goats is significant. Potential shoreline development for tourism, or increased use for water sports could also prove deleterious.
Conservation of this species
Current action
- The main site where globe-flower occurs in Fermanagh is designated by the Environment and Heritage Service (EHS), as Lough Melvin ASSI
- Implementation of the Northern Ireland Habitat Action Plans for Mesotrophic Lakes and Wet Woodland.
Proposed objectives/actions
- Populations of this local and endangered species requires positive management and a program of scientific monitoring.
What you can do
Records of new sites and estimates or counts of the sizes of populations are always valuable. Please do not pick or collect any of this plant. However, do photograph it and send information to The Botanical Society of the British Isles, c/o Department of Botany, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU or to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU. Tel: 028 9039 5256, cedar.info [at] nmni.com.
Further information
Links
Flora of Northern Ireland
Lough Macnean Valley Landscape Character Area
Northern Ireland Habitat Action Plans
Literature
Cooper, M.R. and Johnson, A.J. (1998). Poisonous Plants and Fungi in Britain. 2nd edition. The Stationery Office, London.
Fitter, R., Fitter, A. and Blamey, M. (1996). Wild Flowers of Britain and Northern Europe. Collins Pocket Guide, 5th edition. Harper Collins, London.
Ridley, H.N. (1930). The dispersal of plants throughout the world. Reeve & Co., Ashford, Kent.
Text written by:
Dr Ralph Forbes
iNaturalist: Species account : iNaturalist World Species Observations database