Callitriche hermaphroditica L., Autumnal Water-starwort
Account Summary
Native, occasional. Circumpolar boreal-montane.
October 1906; Tetley, W.N.; Blaney Bay, Lower Lough Erne.
June to October.
Fermanagh occurrence
The Fermanagh Flora database contains record details of this species from 27 tetrads (5.1%), 24 of them with post-1975 records. It is a rather localised, morphologically variable, annual species, which the tetrad map indicates was previously confined to Lower Lough Erne (Revised Typescript Flora). It is now also known from five lake and pond sites on or around Upper Lough Erne, and also from the remote western lakelet of Legalough above Marlbank, where it was found in September 1999 by RHN and HJN. These Upper Lough Erne sites are Killymackan Lough (an ASSI); the shore at Kilmore South Td, N of Rabbit Island; the shore at Crom Td, Lough Corby; and, finally, Lough Nacallagh. Vouchers exist for three of the five Upper Lough Erne sites that emanate from the 1986-7 EHS Habitat Survey of Upper Lough Erne, the 1988-91 NI Lakes Survey and an ENSIS new lake survey carried out in 2006. Greater confidence exists of the correct identification of these particular records than to other un-vouchered records in the Fermanagh Flora Database.
The distribution of C. hermaphroditica appears to closely mirror that of Zannichellia palustris (Horned Pondweed), another submerged species of lowland aquatic habitats with silty substrates that range from mesotrophic to eutrophic in terms of their productivity. The New Atlas hectad map shows that C. hermaphroditica has an essentially northern distribution in B & I. It is certainly much better represented (or better surveyed) in NI than in the RoI, although it does have a thin scatter of occurrences, including remote outlying stations in the far SW in Kerry (H1) and W Cork (H3) and in the SE in Wicklow (H20) (New Atlas).
Threats
Insufficient information exists to determine whether Callitriche species are vulnerable or not.