Anagallis tenella (L.) L., Bog Pimpernel
Account Summary
Native, frequent. Oceanic southern-temperate.
1882; Stewart, S.A.; Drumbad Scarps, Lough Navar Forest Park.
April to January.
Growth form and preferred habitats
This inconspicuous little prostrate perennial with its slender stems and numerous tiny, almost round, pale green or pinkish-buff, sub-opposite leaves is probably quite often overlooked. It creeps and roots at the nodes on the surface of moist to wet peaty or sandy soil, or else trails over the mossy ground carpet of bogs and heathy flushes. It grows in open, almost or fully-illuminated situations, on either bare mud or sandy lake shores or stream sides, on moss-covered bogs, or in short turf marshy, generally flushed ground that frequently supports quite a wide range of flowering plant species, including many of the smaller sedges.
Bog Pimpernel tolerates moderate levels of grazing, trampling and flooding, eg in low-growing sedge areas of marshy grassland, acid fens and beside paths, including in more open areas along woodland tracks. These differing forms of disturbance all clearly allow it and other small plants to survive by keeping the vegetation sufficiently open, creating bare patches, reducing competition and increasing the likelihood of rarer or more local plants occurring.
In coastal areas of B & I, Bog Pimpernel commonly occurs on damp sand in dune slacks, a habitat type we cannot emulate in landlocked Fermanagh.
Fermanagh occurrence

Bog Pimpernel is a quite frequent, by no means scarce species in Fermanagh, being recorded from a total of 84 tetrads, 15.9% of those in the VC. It appears to have lost a few sites, however, since six tetrads have pre-1975 records only. As the tetrad distribution map indicates, the species is decidedly local, being concentrated in the western, wetter, more upland half of the county. That is not to say that Bog Pimpernel is always an upland plant, just that it is more prevalent in upland situations on the constantly moist, nutrient-poor, moderate to strongly acidic, often peaty soils characteristic of the Western Plateau.
At the same time, A. tenella can also be found on the shallow, somewhat drier, raw humus, ranker-type of heath soils formed directly over Carboniferous limestone. These occur, for instance, around the lowland shores of Lower Lough Erne and on the hills above Florencecourt. In such soils, it only grows where sufficient flushing ground water keeps the plant roots moist. Very occasionally, it grows in wet, highly calcareous situations, but it is then never abundant.
Ecological indicator species
Bog Pimpernel is a good indicator of species-rich habitats which are worthy of careful searching for other uncommon acid-tolerant plants, including Drosera anglica (= D. longifolia) (Great Sundew), Eleocharis quinqueflora (Few-flowered Spike-rush), Carex dioica (Dioecious Sedge), C. viridula subsp. brachyrrhyncha (Long-stalked Yellow-sedge), C. limosa (Bog-sedge) and the slightly calcicolous Parnassia palustris (Grass-of-Parnassus).
Flowering reproduction
From June to August, Bog Pimpernel bears a mass of erect, relatively long-stalked, small, solitary, pale pink flowers. The petals are finely striped with purple and the centre of the upright funnel-shaped flower is filled with fluffy white hairs on the filaments of the five stamens, making them absolutely beautiful when viewed in close-up.
Very little appears to be known or certain about the reproductive biology of the species. The flowers are visited by insects, but they are also capable of selfing (Fitter 1987). Seed is dispersed in mud by ducks and other waterfowl (Ridley 1930, p. 547). One reference exists, dating from 1934 that claims seed is long-term persistent (ie surviving more than five years in the soil) (Thompson et al. 1997). Despite its name (see below), the plant is not tender but perfectly hardy in our western oceanic climate at least. Having said this, garden cultivated forms are described by Grey-Wilson (1989) as "short-lived and may be killed in a severe winter".
Apart from the Grey-Wilson's comment, the current author (RSF) can discover nothing in the literature on the population biology of A. tenella.
British and Irish occurrence
The New Atlas map shows that in B & I the distribution of the species has a pronounced western predominance, although it does also display a complete south-north latitudinal range – although very definitely thinning in frequency towards the NE and the much drier SW of Britain. This trend again suggests a possible low temperature limitation. On the other hand, the altitudinal limit of the species appears to be as high as 610 m in N Aberdeen (VC 93), while in Ireland it reaches 490 m in both the Mourne Mountains, Co Down (H38) and in the far SW on the very highest Irish mountains, the Macgillycuddy's Reeks in S Kerry (H1), indicating the plant demonstrates considerable frost resistance (Wilson 1956; A.J. Richards, in: Preston et al. 2002).
The English distribution includes a disjunct E coast presence, clearly reflecting the occurrence of Bog Pimpernel in its dune slack habitat. In Ireland, A. tenella is more generally distributed in comparison with Britain, the pattern here mirroring the highest levels of precipitation and general hydrology (Haughton et al., Atlas of Ireland, 1979, pp. 22, 32).
There undoubtedly have been losses of A. tenella in Fermanagh and elsewhere throughout B & I in recent decades, although the New Atlas Change Index of -0.54 really is a moderately low figure. Losses have been consequent upon the drainage of lowland bogs and marshes, but also through a general nutrient enrichment associated with agricultural changes and grassland 'improvements' over the last half century.
European occurrence
The wider, essentially milder-European region distribution of A. tenella puts it firmly into the Oceanic Southern Element of Matthews (1955), which comprises 76 species disregarding those now recognised as introductions, a category more recently refined as the Oceanic Southern-temperate (25 species) by Preston & Hill (1997). Most of the species in this grouping have their northern limit in Britain but, rather exceptionally, A. tenella is a very rare member of the coastal flora of the Faeroe Isles which lie at 62°N (Ostenfeld & Grontved 1934). The only other Oceanic Southern-temperate species to approach this northern range is Eleogiton fluitans (Floating Club-rush) (another plant of wet, peaty habitats), which on the European mainland reaches around 57°N in S Sweden and is also present in Shetland around 60°N.
At its southern limit A. tenella has outlying localities in N Africa, W Greece and NW Crete (Hultén & Fries 1986, Map 1483; Turland et al. 1993, Map 1050).
Names
The Latin specific epithet 'tenella' is a diminutive meaning 'tender' or 'delicate', the latter more fitting when the very beautiful flower is being closely admired (Gilbert-Carter 1964). As noted above, the species is perfectly hardy in our climate, and could not overall be described as tender.
Threats
Drainage, eutrophication and changing land use.