Hieracium agg., Hawkweeds
The tetrad map of this aggregate, taken together with the few records for eleven of the many Hieracium microspecies or Sections, very clearly demonstrates just how much yet remains to be learnt about hawkweeds in Fermanagh. This map does not include records for Pilosella officinarum (Mouse-ear-hawkweed) but, nevertheless, it plots records from just 35 Fermanagh tetrads, 6.6% of the VC total. As the map indicates, hawkweeds are recorded mainly in the western uplands and they generally occur on cliffs, usually of limestone, or in ground flushed with base-rich waters.
The Hieracia are a group of tap-rooted perennials that almost all set seed asexually without pollination taking place, ie they reproduce apomictically, without any genetic mixing or crossing between plants. As a result of this, they are genetically fixed, locked away in an evolutionary 'cul de sac'. Currently these hawkweed forms are believed to consist of 412 microspecies (Sell & Murrell 2006, p. 223), some of which are known from only one site in B & I. The microspecies belong to sections that previously made them somewhat easier to delimit, key and recognise. The treatment in An Irish Flora (6th edition, 1977), which the current author (RSF) and RHN relied upon during most of their survey of Fermanagh flora, handled the variation in terms of six basic 'Groups' or Sections. It now transpires that hybrids occur particularly between two of the Hieracium sections and the key characters that define the sections are the most difficult to understand (P. Sell, in: Sell & Murrell 2006, p. 223).
As with the dandelions, however, they constitute a critical taxonomic group that requires the collection of vouchers and their dispatch to specialist referees. Thus, due to pressure of time and other more urgent recording priorities, Irish field botanists until now have seldom bothered very much with hawkweeds; they either simply lump them into the aggregate, or they ignore them.
Unless visits are made to Ireland by experts in the known critical groups, who are willing to spend time both collecting and identifying material and tutoring and encouraging local field workers in the basics of the subject, the general (near total) lack of recording effort on the island is bound to continue. It is just a little comforting and spares any blushes that the paucity of Fermanagh Hieracium records in this present work is mirrored to a certain extent in a number of other B & I county Floras of recent years. It is acknowledged that the problem in dealing with critical groups is certainly not unique to Fermanagh recording, but it is definitely far greater and more difficult to overcome when there are only one or two regular plant recorders resident in a VC.
The publication in 2006 of the relevant volume of the critical Flora of Great Britain and Ireland contains an up-to-date treatment by P. Sell, which should certainly make a major difference to the identification of hawkweeds in future (Sell & Murrell 2006).
Apart from a few weedy examples, hawkweeds are chiefly calcicole, montane or submontane perennials, which in Fermanagh only produce small populations in infertile, rocky sites inaccessible to grazing animals, such as on cliffs, steep talus slopes, on stonework of bridges, or on roadsides or hedgerow embankments. The wet, acidic nature of many of the soils in the VC also makes them unsuitable for hawkweeds and, taken together with the large number of sheep, cattle and feral goats browsing, no one would expect a vast range of this plant group to be present.
References
Sell & Murrell 2006; An Irish Flora 1977