Isoetes echinospora Durieu, Spring Quillwort
Account Summary
Native, very rare, possibly a mis-identification. Circumpolar boreal-montane.
1946; MCM & D; Castle Caldwell, Lower Lough Erne.
Fermanagh occurrence
Just two Fermanagh records exist from peaty or muddy lake bottoms, at Castle Caldwell, listed above and Bunnahone Lough in 1947, made by Meikle and his co-workers. The Revised Typescript Flora noted that, "These identifications need checking, as do all Irish Isoetes records." (Meikle et al. 1975). In Meikle's Fermanagh Flora card index, the Bunnahone plant was originally recorded as I. lacustris but was later reassigned. As far as we are aware, no vouchers exist for I. echinospora from Fermanagh (Osborne & Doyle 1992).
Nowadays, both sections of Lough Erne are eutrophic to hypertrophic and thus have become too nutrient-rich to support either species of Isoetes. However, in 2006 and 2007, palaeoecological studies associated with water quality assessment took sediment cores from several N Ireland lakes including the Trannish region of Upper Lough Erne and Meenatully Lough on the Pettigo Plateau blanket bog. These very different waterbodies contained fossil megaspores of both I. echinospora and I. lacustris. In the case of Meenatully Lough, macrofossils of both species were present in the lower portion of the upper 0-7 cm zone of the core, dated post-1970 (Davidson et al. 2008). The N Ireland Lakes Survey (1988-90) recorded only I. lacustris in this lake.
Irish occurrence and status
Although it did not feature or deserve a mention in the Irish Red Data Book. 1. Vascular plants (Curtis & McGough 1988), I. echinospora is now classified as a scarce species by conservationists in the Republic of Ireland. In our view, it is better described as a rare and possibly declining species. The known Irish stations are extremely thinly scattered down the W coast from Co Donegal to Co Kerry (Preston & Croft 1997). There are voucher specimens in DBN for six of the 40 Irish VCs, but only those of Co Clare (H9) are modern, all the rest being pre-1911.
Only ten of the total of 41 Irish records held at the Biological Records Centre, Wallingford, Oxfordshire are post-1950. They represent occurrences in five Irish VCs, S Kerry, N Kerry, Co Clare, W Galway and W Mayo (H1, H2, H9, H16 and H27). [All but the two records from S Kerry (H1) are from sites below 100 m in altitude (Osborne & Doyle 1992). I. echinospora is probably slightly more frequent in Co Clare (H9) and W Galway (H16), since these two VCs share six of the ten post-1950 records between them (Webb & Scannell 1983; Osborne & Doyle 1992).]
Identification difficulties
It is very difficult to distinguish I. echinospora from I. lacustris (Quillwort) in the field and they can co-exist and hybridise. The fact that specimens require microscopic confirmation deters the more casual recorder, so that I. echinospora may be overlooked or mistaken by field botanists for the very much more common species (Jermy & Camus 1991; Page 1997). Very sensibly in their Flora of Connemara and the Burren, Webb & Scannell (1983) were chary of accepting any reports of Spring Quillwort that had not been verified by microscopic examination of the microspores, a procedure which Osborne & Doyle (1992) also regard as absolutely essential.
In addition to the absence of vouchers for the 1940s Fermanagh records, the systematic survey of our lakes made in recent years has failed to find living specimens of I. echinospora. We therefore believe that either Meikle and his co-workers misidentified their specimens, or subsequent field workers (including ourselves) have not looked carefully enough at Isoetes material, especially that occurring in more oligotrophic waters.
Names
The genus name 'Isoetes' appears to have been coined by the ancient Roman scientist Pliny, combining two Greek words 'isos', meaning 'equal' and 'etos', meaning 'a year', ie 'equalling one year'. This refers to the idea that the plant did not change with the seasons, meaning that it was evergreen. However, it is also thought that Pliny originally applied the name not to this species, but rather to a member of the Crassulaceae (Gilbert-Carter 1964; Johnson & Smith 1946). The Latin specific epithet 'echinospora' means 'spiny spored', which is for once, the major defining character of the species.
Threats
None.