Asplenium viride Huds. (Asplenium trichomanes-ramosum L.),
Green Spleenwort
Account Summary
Native, rare. Circumpolar boreo-temperate.
1860; Smith, Rev Prof R.W.; Florencecourt area.
Throughout the year.
Growth form and preferred habitats
This little evergreen perennial fern is generally described as a calcicole species, ie one which is lime-tolerant and/or preferring or requiring base-rich conditions. The frond has a delicate texture and the green rachis is extremely distinctive. A. viride requires much higher levels of humidity than A. trichomanes (Maidenhair Spleenwort) and will grow in conditions of considerably deeper shade. Unlike A. trichomanes and its subspecies, the rachis of A. viride does not shed its pinnae, but rather when it withers the whole frond shrivels and only a very short persistent brown base remains (Page 1997; Jonsell et al. 2000).
Normally the species does not tolerate drought or high summer temperatures, and while in natural rock habitats it regularly associates with A. trichomanes s.l., A. ruta-muraria (Wall-rue) and Cystopteris fragilis (Brittle Bladder-fern), unlike these three ferns it is generally absent from walls. All Fermanagh records for this species are from naturally occurring rock habitats (ie cliff faces, crevices, ledges and limestone grykes and swallow holes), but in some areas of Britain and Ireland A. viride has also been rarely found growing on lime-mortared walls (Jermy & Camus 1991).
Fermanagh occurrence
In Fermanagh, Green Spleenwort is rare, never abundant and has been recorded in a total of just eight tetrads. Although a rare species, it is most abundant in several of the deep limestone swallow holes near Legacurragh above Florencecourt in the south of the county, where it grows as tufts on the vertical faces of the rock. It also occurs sparingly on both the dolomitized Upper Visean sandstone and shale, and the dolerite and basalt scarps in the Lough Navar area (Woodland et al. 1977). As the tetrad distribution map indicates, in addition to the rather isolated Legacurragh site, A. viride also has a second outlier on an isolated scarp near Lough Alaban in Tullyloughan Td, Carrigan Forest. The fern population here consists of just six plants. The range of substrates mentioned demonstrates that while Green Spleenwort always occurs on soils derived from base-rich rock, it does not necessarily require a high calcium content in the soil it occupies (Jermy & Camus 1991).
British and Irish occurrence
In Britain, Green Spleenwort has a distinctly N, W and upland distribution, with the greatest concentration of records occurring N of a line from Morecambe to Bridlington. In Ireland, by comparison, it is very much less frequent overall, and it is distinctly western and montane, being confined to moist, shaded habitats in areas with low summer temperatures (Jermy et al. 1978).
European occurrence
In Europe, A. viride is widespread on calcareous and other base-rich rocks, but further south it is found mainly in the mountains, while in Fenno-Scandinavia it has a north-western and Atlantic concentration (Jalas & Suominen 1972, Map 83; Jonsell et al. 2000). We could thus describe its European range as being rather similar to that of an Arctic-alpine or Arctic-montane species, but with an additional more lowland boreal occurrence (Page 1997). In Fenno-Scandinavia, A. viride has been described as being particularly frequent on ultra-basic rock (eg serpentine), and under such unusual and generally toxic soil conditions in those latitudes, it can also be found in much drier, sun-exposed sites than is the case elsewhere (Jonsell et al. 2000).
World occurrence
The world map features the species with an uneven distribution in boreal northern and eastern Europe, and then a rather discontinuous, disjunct circumpolar occurrence through NW Africa, Turkey, the Caucasus, the Urals, mountains of S Siberia and C Asia, W Himalaya, Japan, W & E North America, S Greenland and S Iceland (Hultén 1962, Map 92; Hultén & Fries 1986, Map 43; Jonsell et al. 2000).
Names
'Asplenium' is derived from the Greek 'a' meaning 'not' and 'splen', 'splene' or 'splenon' referring to the spleen, alluding to the supposed medicinal properties of the fern genus. The herbal medicinal use is also invoked by the English common name applied to the genus, ‘Spleenwort’ (Hyam & Pankhurst 1995). The Latin specific epithet ‘viride’ means either ‘youthful’, or rather better, ‘fresh green’. The English common name is a simple translation of the Scientific name, ‘Green Spleenwort’.
Threats
None.