Utricularia australis R. Br., Bladderwort
Account Summary
Native, very rare. Eurasian boreo-temperate, reportedly introduced in C & S Africa, Australia and New Zealand.
July 1946; MCM & D; Mount Sedborough Lough.
As noted under the account of U. vulgaris s.l. (Greater Bladderwort), this segregated aquatic perennial species can only satisfactorily be distinguished when in flower, and since these two taxa (ie U. australis and U. vulgaris s.s.) more often than not are found without flowers in northern parts of B & I, including Co Fermanagh, the true distribution of them may never be properly known.
Meiosis in U. australis is abnormal and the pollen of the species, unlike that of U. vulgaris s.s., is often abortive (Caspar & Manitz 1975). Probably on account of this, there is no record of any B & I populations setting seed and reproduction must, therefore, depend entirely upon vegetative turion (ie leafy bud) production. Despite the extensive world distribution of U. australis, mature fruit have only been reported from China and Japan (Taylor 1989). The species appears to reproduce purely by vegetative means everywhere else it occurs, which includes most of Europe northwards to C Scandinavia. It is also found in temperate and tropical regions of the Old World and in Australia, where it is considered indigenous (Preston & Croft 1997). It is introduced in New Zealand (Webb et al. 1988).
Like the more commonly found U. vulgaris, U. australis occurs in still or sluggish water in drains and swamps around sheltered lakeshore bays but, as far as can be told, it tends to occupy more base-poor, acidic waters than the former. Having said that, it is not unknown for it to occur in calcareous sites in both B & I (Preston & Croft 1997).
Fermanagh occurrence
There are records of this species from a total of nine sites in the Fermanagh Flora Database. Interestingly, the tetrad map shows that the sites are grouped at both the NW and SE ends of the VC.
The details of the other Fermanagh records are: W shore of Kilmabrack Lough, 1949, MCM & D; Gadalough, N of Keenaghan Lough, 1950, MCM & D; and shallow water 1.5 km E of fishing area at Lowery, Lower Lough Erne, 28 July 1976, Miss Nora Dawson. At the latter site, the plant was flowering freely. In August 2006, a special lake survey carried out for NIEA by English-based field workers (ENSIS) recorded U. australis at five sites: all three Knockballymore Loughs, plus Summerhill Lough and Kilroosky Lough ASSI. It is interesting that despite all the other lake recording that has gone on in Fermanagh in the 30 years between 1976 and 2006, nobody had claimed to have found this species.
Threats
None apparent, although since the species is not readily discerned vegetatively, it could possibly be under threat without the fact being apparent.
References
Caspar & Manitz 1975; Taylor 1989; Preston & Croft 1997; Webb et al. 1988