Hottonia palustris L., Water-violet
Account Summary
Introduced, neophyte, rare and now locally extinct. In its native range, European temperate and protected in NI.
1939; Carrothers, E.N.; Whinnigan Glebe Td, near Farnaght.
Fermanagh occurrence
This submerged, shade-tolerant, truly aquatic member of the Primulaceae has not been seen since about the 1950s at its only reported Fermanagh station, the bog holes and adjacent drains at Whinnigan Glebe Td, about 7 km from Enniskillen. This brief habitat description does not sound very suitable for the survival of the plant, since H. palustris really prefers clear, mesotrophic, base-rich, usually calcareous waters (Preston & Croft 1997; A.J. Richards, in: Preston et al. 2002). In the Revised Typescript Flora, Meikle et al. (1975) followed Praeger (1939) in stating quite unequivocally that the plant was introduced from the Bog Meadows in SW Belfast, some time around 1920. The site at Whinnigan Td lies just beside the Carrothers' family farm at Farnaght, so we believe that the plant was most likely introduced there by N. Carrothers, ie the older Carrothers naturalist. Praeger (1939) listed the next generation family member, R.D. Meikle's co-worker, E.N. Carrothers, as his source for the record of the Fermanagh introduction.
The Bog Meadows in SW Belfast, from which the Fermanagh plant derived, was itself an introduction of this species. It is known that John Templeton, one of the most talented early Irish naturalists, transferred the plant to his garden at Cranmore in south Belfast in the early 19th century. He collected his material in the River Quoile marshes around Downpatrick, Co Down (H39), where the first Irish discovery of this wintergreen aquatic perennial was made by a Mr Richard Kennedy in June 1810. The original site was described as, "in the marshy ditches on the right side of the road at Everogue bridge, near Downpatrick" (FNEI 1).
The flowers and submerged leaves are attractive so that H. palustris is nowadays commonly used to decorate and oxygenate garden ponds and fish-tanks. The species is heterostylous and requires crossing between pin and thrum flowers to set seed. Being stoloniferous and capable of vegetative reproduction by fragmentation, the plant often produces single-morph colonies which fail to set seed. H. palustris should be capable of long-distance jump dispersal through the movements of water fowl, as this is presumed to have occurred elsewhere in these islands (McCallum Webster 1978; Hackney et al. 1992). An interesting summary of the biology, ecology and distribution of the species is provided in Preston & Croft (1997).
Irish occurrence
In Ireland, this very attractive stoloniferous perennial is a very rare species which has been reported in a small number of other scattered Irish counties, all of which stations are known or deemed introductions. A small (but presumably sexually reproducing) population survives, totally submerged apart from the flower spikes, in deep, peaty, ditches, dug in a wood at Hollymount NR near Downpatrick and in the nearby marshes (VC H38). These sites are the only candidates for possible Irish native status. In NI, it is protected under Schedule 8 of the Wildlife (NI) Order, 1985.
British occurrence
In England and Wales, H. palustris is quite frequent and widely scattered south of a line on the map between Sunderland and Holyhead and locally common in eastern England. However, with the exception of the Bristol area, it is poorly represented west of a line between Chester and Worthing on the S coast. Isolated occurrences in C Scotland and the Isle of Man are regarded as definite introductions (New Atlas).
Sites have been lost in Britain due to drainage, vegetation clearance from waterways, eutrophication and boating disturbance beginning prior to the 1930s, but continuing to the present, especially in SE England (A.J. Richards, in: Preston et al. 2002).
European occurrence
H. palustris is mainly restricted to middle latitude areas of Europe, although it reaches north as far as C Sweden and southwards to S France, C Italy and Romania (Hultén & Fries 1986, Map 1475).
Threats
Drainage, eutrophication and collection.