Conservation of Britain’s biodiversity: Distribution and status of the Welsh endemic Hieracium britannicoides, Confused Hawkweed (Asteraceae)

Hieracium britannicoides, Confused Hawkweed, is a Welsh endemic plant confined to Caernarvonshire (v.c.49) and Denbighshire (v.c.50). Field surveys 2009-2019 indicate at least 390 plants occur in eight sites. The IUCN threat status is ‘Vulnerable’. The main threats are spread of alien woody species (especially Cotoneaster), which without continued management will become a serious problem in the future, and over-grazing or spread of scrub from under-grazing.


Introduction
Hieracium britannicoides P. D. Sell, Confused Hawkweed, was first described as a species by Sell & Murrell (2006) who separated it from other members of the H. britannicum group. Bevan (1990) gave the first detailed account of H. britannicoides (as H. britannicum) in Wales.
Hanb. and gave its distribution as Derbyshire (v.c.57), Staffordshire (v.c.39),, and possibly Fife (v.c.85). Further records followed including the first Welsh records in Caernarvonshire (v.c.49) (Linton, 1905). Subsequent studies showed there was significant variation within H. britannicum, and it was split into a number of geographically separated species including two in North Wales: robust plants with spotted leaves were named as H. britanniciforme Pugsley (Pugsley, 1941) and the relatively small plants with unspotted leaves as H. britannicoides (Sell & Murrell, 2006). Hieracium britannicum sensu stricto is now regarded as confined to Derbyshire and Staffordshire (Sell & Murrell, 2006). Hieracium britannicoides is characterised by having rosettes with ovate, obtuse rosette leaves with subtruncate bases often with retrorse teeth and sparsely hairy or glabrous above with few to numerous simple eglandular hairs beneath, the absence of stem leaves (or sometimes a very reduced ±linear leaf), the few-headed inflorescences with 2-6 capitula, the involucral bracts with few to numerous stellate hairs (especially near the base), numerous dark glandular hairs and numerous simple eglandular hairs, and yellow styles (Figs. 1-3). Hieracium britannicoides is intermediate morphologically between H. britannicum and H. britanniciforme and has at separate times been included in both of them (Sell & Murrell, 2006); it clearly merits its common name 'Confused Hawkweed'.

Figure 2. Hieracium britannicoides. Bryn Euryn (type locality)
In North Wales, H. britannicoides is readily distinguished from H. britanniciforme by its smaller size and the absence of spotting on the leaves. In a few sites it grows with H. vagense (F. Hanb.) Ley, which is normally easily distinguished by its laciniate leaves but some H. vagense plants in droughted habitats have small, lanceolate, acute more or less untoothed leaves which can then be distinguished by having dense glandular hairs and few simple hairs on the involucral bracts (H. britannicoides bracts are greyish-hairy due to the numerous simple hairs with white tips). Hieracium pseudoleyi (Zahn) Roffey also occurs with it on parts of the Great Orme and Little Orme; this is distinguished by its narrower leaves (Sawtschuk et al., 2008). The 'look-see' method (Hill et al. 2005) was adopted for data collection as it was the most appropriate method to survey the sites which had many inaccessible areas on cliffs, thus the population counts provide minimum population estimates. At each site, the location was recorded using GPS and the number of plants counted. Ecological notes on the vegetation types were made for most sites (here referenced in terms of British Plant Communities; Rodwell et al. 1991Rodwell et al. -2000.

Results
The historical records (Table 1) and field work indicate H. britannicoides occurred in eight sites in two vice-counties (Fig. 4)   Like its relatives, H. britannicoides is likely to be a polycarpic and apomictic but this has not been tested experimentally. It typically flowers in May and June, sometimes extending into July and occasionally again in the autumn. 49% of the plants seen in 2010 were flowering or fruiting; seed set appeared to be high.
All of the populations occur in sites designated as Sites of Special Scientific Interest (SSSI) and some were in nature reserves or Special Areas for Conservation (SAC). There was no evidence for loss of sites or decline and the species appears stable. The only immediate threat is the spread of alien woody species such as Cotoneaster microphyllus and Quercus ilex, both of which can grow on the limestone rocks and shade the hawkweeds. Extensive work has already been carried out to control these alien plants at Bryn Euryn, Great Orme, Little Orme and Mynnydd Marian; without continued management these will become a serious problem in the future for H. britannicoides and the many other rare plants which occur in this area.
As most populations occur on relatively inaccessible cliffs, grazing mainly restricts populations to steep areas out of the reach of sheep and goats. Hawkweeds in general are highly palatable and consequently sensitive to over-grazing by stock. Grazing may be a key part of site management and it is likely that any stock grazing during the growth season (c. March to October) will eliminate it from accessible areas. The smallest population is on the Little Orme which is also the most heavily sheep-grazed site. It is unclear if the goats on the Great Orme eat it. In contrast, on the steep northfacing cliffs at Mynydd Pant and Nant y Gamar it is at longer term risk from scrub/woodland invasion which may eventually shade out the plants.
Seeds of H. britannicoides have been collected from the Great Orme with consent and deposited in the Millennium Seed Bank for ex situ conservation.