Populus nigra L. subsp. betulifolia (Pursh) Dippel, Black Poplar
Account Summary
Probably planted, rare, but at least some identifications need verification. Circumpolar boreo-temperate.
1912; Druce, Dr G.C.; Co Fermanagh.
June to October.
Growth form and preferred habitats
Black Poplar is an uncommon, large, rough-barked, dioecious, deciduous tree of lowland hedges on flood plains along rivers and around lakes. Previously, Black Poplar was considered indigenous only in S England and E Wales, although even here the tree has also been regularly and widely planted as an amenity or specimen tree in urban locations, since it is very tolerant of industrial pollution (Milne-Redhead 1990; Cottrell et al. 1997). The previous regular plantation of Black Poplar, which was highly prized for its timber, appears to have been superseded in B & I by the introduction of hybrid trees as early as the end of the 18th century (Hobson 1993).
Recently, Black Poplar was recognised as a native tree in Britain under imminent threat of extinction due to the old age of many specimens, the general lack of new plantations for very many years and the fact that planting female trees had been avoided due to the local mess made by the dispersal of their fluffy seed. The realisation of the tree's rarity then stimulated surveys which have now been carried out in both Britain (Milne-Redhead 1990) and in parts of the RoI by Hobson (1991, 1993). The results of the survey in Britain recognised that the majority of trees were derived from planted cuttings, frequently resulting in local clones of a single sex. Very few locations are known in Britain where the two sexes co-exist and therefore the vast majority of reproduction is vegetative, either by root suckers or by fragmentation and re-rooting. In the very rare locations where viable seed is formed, seedling survival requires a prolonged period of bare wet mud substrate, habitat conditions which are rarely met nowadays in the intensively managed lowland wet landscape of Britain. For these reasons, seedlings and saplings are almost unknown in the British survey (see Milne-Redhead 1990, p. 3).
Fermanagh occurrence
Ten of the 13 Fermanagh records in eleven tetrads that exist for Black Poplar in the Fermanagh Flora Database are from the 1986-7 DOENI Upper Lough Erne survey, but probably all of the local records of this taxon require verification. The Fermanagh trees are principally located on or near the Crom Castle estate at the southern end of Upper Lough Erne and we are fairly confident that if they are correctly identified in the first instance, they would almost certainly be of planted origin in such a setting.
Irish occurrence and status
Hobson's survey in southern Ireland found that the tree was exclusively associated with river valleys and flood-plains, often in sites remote from farms and other habitation. The tree was widespread in these situations, which were not as expected, concentrated in 'the English Pale' around Dublin and the adjacent eastern counties. On this basis, Hobson (1991) suggested that Black Poplar might possibly be a native Irish tree. If this is so, it is interesting that young specimens not more than ten years old were also located during the survey. These probably indicate that some Irish farmers continue to plant local Black Poplars instead of using imported hybrid stock. The useful timber the tree produces helps explain its plantation in these cases (Cottrell et al. 1997). Hobson (1993) found a quite extensive Irish population with a well-balanced age structure, which again suggests ecological stability here. Furthermore, around Lough Ree and Lough Allen he discovered it is still naturally regenerating in the wash zone of winter storms.
Threats
None.