BSBI Species Accounts ArchiveCrepis mollis
Thu, 08/26/2010 - 14:47 | 
markd
Scientific name: Crepis mollis (Jacq.) Asch.
Synonyms: Crepis hieracioides Waldst. & Kit., Crepis succisifolia (All.) Tausch, Hieracium molle Jacq.
Common name: Northern Hawk’s-beard, Soft Hawk’s-beard
Three subspecies are currently recognised on the continent (ICN 2009). There appears to be no history of recognising intraspecific taxa in Britain. In a thorough account of Crepis, Babcock (1947) divided the genus into 27 Sections, based on chromosome shape & number as well as gross morphological characters. He places Crepis mollis in Section Mesomeris. Recent combined DNA and morphological work on the genus revises the relationships between the species significantly (Enke 2008). Enke’s study mostly does not support Babcock’s sectional division, apart from Section Mesomeris which corresponds to Enke’s Clade 1. Despite the morphological similarities between Crepis and Hieracium (see below), Crepis is closer genetically to Lactuca and Taraxacum than it is to Hieracium, which is placed in a separate subtribe (ICN 2009).
Chromosome No.: 2n = 12 (Stace 2010).
Photography: K.J. Walker
A difficult species to identify, which is probably both overlooked and occasionally recorded in error. Useful line drawings are included in Silverside (1990) and Ross-Craig (1962). The arrangement of the involucral bracts is not as obviously in two distinct whorls as in most other species of Crepis in Britain. It is very close morphologically to some Hieracium species, in particular those that have mid and upper stem leaves with semi-amplexicaul bases and relatively unobvious marginal teeth. Those most likely to be confused with Crepis mollis may include Hieracium prenanthoides and several species from Section Foliosa. When these Hieracium plants grow in particularly stressed environments they may produce fewer and smaller leaves than normal, making them more difficult to separate from Crepis mollis. Pappus colour is given in many field guides as a useful way of distinguishing Crepis (white pappus, apart from Crepis paludosa) from Hieracium (off-white, dirty white to pale brown). The pappus of Crepis mollis is said by some to be ‘glistening white’. However, Hieracium taxa vary considerably in pappus colour and some forms of Crepis mollis on the Continent are said to have a brownish pappus. Records of Crepis mollis need to be treated with caution, preferably by expert checking of the plants in situ rather than collecting specimens, due to its current rarity. If this is not practical, then photographs and/or specimens of a mid-stem leaf and a ripe capitulum should be taken.
Within Europe its distribution is temperate, European (Hill et al. 2004), occurring from the Pyrenees and Northern Italy northwards to Germany and the Baltic states and from Britain eastwards to Ukraine and western Russia (ICN 2009). It does not occur outside Europe. Its current British distribution includes the northern half of the Pennines from the Yorkshire Dales northwards to the Cheviots and adjacent hills in north Northumberland and the Scottish borders, with more scattered records further north, mainly in the east Highlands. Its main populations are centred on Northumberland and the Scottish borders, being much rarer to north and south, which is quite an unusual distribution for a British native plant. There are number of old records in more scattered localities, at least some of which are doubtful. It has not been seen in North Wales or in v.c. 62 for about 100 years. Even more unusual records come from lowland areas in east Durham, south Cumbria and southern counties of England. At least two of these records are backed up by specimens in museums which have not, however, been checked for this account. Similar doubts may apply to some of the older Scottish records (e.g. see McCallum Webster 1978).
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- Origin: Native in England, Scotland and Wales. First British record is from 1794 (Clark 1900).
- Rarity: Nationally scarce (Stewart et al. 1994). Preston et al. (2002) shows 84 hectads in all time classes. Both Braithwaite (1996) and Preston et al. (2002) point out that although it appears to be declining, it is under-recorded and new sites are still being found. However, a concerted effort was made to search for it at many of its former sites in 2008 as part of BSBIs threatened plants project (TPP) but only 56% (19 out of 34) of randomly selected populations were refound. Overall, since 2000, it has been recorded from only 24 hectads in England and Scotland (including at a small number of newly discovered sites). It has not been seen at many of its former sites for 100 years or more.
- Threat: Listed as ‘Endangered’ (Cheffings & Farrell 2005). It is given a change index of -1.20 in Preston et al. (2002), ‘a substantial decline in last 30 years of twentieth century’.
- Conservation: listed as a UKBAP priority species since 2007. However, no national targets have been set for this species under the BAP process and it does not appear to be mentioned in any county BAPs. Listed as an axiophyte in all three of the counties within its range which have axiophyte lists.
A sub-montane species in Britain with an altitudinal range from 90 m to 670 m (Preston et al. 2002), but usually between 150 m and 400 m (Braithwaite 1996). It was refound at 725 m in Caenlochan by Eric Meek in 2009 (Kevin Walker pers. comm.). It is assigned the following Ellenberg Indicator Values in (Hill et al. 2004): L = 8, light-loving plant, rarely found where relative illumination in summer is less than 40%; F = 5, moist site indicator, mainly on fresh soils of average dampness; R = 7; weakly acid to weakly basic conditions, never found on very acid soils; N = 5, sites of intermediate fertility; S = 0, absent from saline sites. However, regarding the L value given above, it still occasionally occurs in open woodland, and at one site in Northumberland in a quite shaded situation along an old railway line through a forestry plantation. Therefore, an L value of 6 or 7 may be more appropriate. It has no means of vegetative spread (Hill et al. 2004). It is not mentioned as a constituent species of any NVC communities in Rodwell (1992), which is not surprising due to its rarity and the fact that no vegetation samples were recorded for the NVC project from MG3c, which is one of its main modern habitats. The best available evidence of its current British ecology comes from the associated species and environmental data collected in 2008 for TPP. A preliminary examination of these data suggests it was found in the following types of vegetation: unmanaged or infrequently managed, species-rich grassland on banks and verges with other northern-montane species (neglected upland hay meadow vegetation or MG3c) appears to be the most common habitat. It also occurred in similar habitats without other northern-montane species (MG1e or MG5c). Occasionally, small populations were found in long-neglected, more rank and species-poor, bank and verge vegetation (MG1b, MG1c, M27a & MG9). In some sites the vegetation resembled a form of MG2, a sub-montane woodland glade type of vegetation that includes northern-montane species as well as woodland herbs and ferns. Some of these sites may in fact have been from W9 woodland habitats, which would not necessarily have been picked up by the survey method. One site resembles M26b, which is a species-rich and base-rich, sub-montane type of wet grassland that occurs rarely in upland hay meadows. Only one other sample was from a truly calcareous vegetation type (CG2), but several of the samples from mesotrophic grassland were on the base-rich side of mesotrophic and included other calcicole species. It appears to currently occupy different habitats in different parts of its British range. Braithwaite (2004) notes an association with intrusive rock in Berwickshire. There may be an association with intrusive rocks at some of its Teesdale locations, but this association has not been noted elsewhere. In Yorkshire and Cumbria many sites have a strong limestone influence. In Northumberland where a large proportion of its surviving populations are found, it is not strongly associated with intrusive rocks or limestone and most often occurs in unmanaged grasslands including on road verges, riverbanks and unmown banks in meadows. There is some evidence that two aspects of its main British habitats have changed over the past 100 years. Old floras frequently mention denes, thickets and woods, but most modern records are from more open habitats. Swan (1962) reports on failing to refind it in many of the old hill dene sites in Northumberland, but finding it in several new, more open, sites. Secondly, it is now found more frequently in unmanaged verge or bank vegetation compared to meadows that are still mown annually. Prior to large scale agricultural improvement it may have been more frequent in mown meadows than it is now. Its preference for meadows and lightly grazed or ungrazed situations may indicate that it is only moderately tolerant of grazing. It can tolerate annual mowing, and its relative absence from modern mown species-rich meadows may be due to the overall decline in quality of meadows due to agricultural improvement compared to verge vegetation. One or more of the following aspects of agricultural improvement may be behind its decline: artificial fertiliser applications; changes in type and/or amount of farmyard manure used on meadows; more intense spring grazing; earlier cutting dates; switch from hay-making to haylage-making; soil compaction. The following information on its preferred habitats on the continent is based on data compiled by Kevin Walker from various European floras. Most floras give hay meadows as the habitat. Interestingly in Estonia, Lithuania, Poland and southern Bohemia, wet, flooded or floodplain meadows are specifically mentioned - a habitat which it does not occupy in Britain. Several floras including eastern Germany, Czech Republic, Slovakia & Switzerland mention similar montane and sub-montane meadow vegetation to our MG3.
This species is included in the BSBI Threatened Plants Project. Which subspecies are present in Britain? As it is incapable of spreading vegetatively, it is reliant on reproducing from seed. How long do individual plants live and so, how often does it need to establish new individuals to maintain its populations? How viable are its seeds and what factors influence seed viability and seedling establishment. How long does it persist in unmanaged banks and verges that gradually become more overgrown over time? What is the optimum management regime for these currently neglected habitats to conserve their biodiversity interest?
Acknowledgements: Jeremy Roberts and Kevin Walker gave constructive comments on a draft version and in particular helped make the Ecology section more geographically balanced. Thanks also to Vincent Jones for a useful conversation about possible lookalike species in Hieracium.
- Babcock, E.B. 1947a. The Genus Crepis I. The Taxonomy, Phylogeny, Distribution and Evolution of Crepis. University of California Publications 21. University of California Press, Berkeley & Los Angeles.
- Babcock, E.B. 1947b. The Genus Crepis II. Systematic Treatment. University of California Publications 22. University of California Press, Berkeley & Los Angeles.
- Braithwaite, M.E. 1996. Crepis mollis. In Scarce Plants (Stewart, Pearman & Preston). Braithwaite, M.E. 2004. Berwickshire rare plant register 2004. M.E. Braithwaite. Hawick.
- Enke, N. 2008. Phylogeny and character evolution in the genus Crepis L. (Cichorieae, Compositae). PhD Thesis. Free University, Berlin.
- Hill, M.O., Preston, C.D. & Roy, D.B. 2004. Plantatt. Attributes of British and Irish plants: status, size, life history, geography and habitats. Centre for Ecology and Hydrology, Monks Wood, Cambridgeshire.
- ICN (Hand, R., Kilian, N & Raab-Strube, E von; general editors) 2009 -(continuously updated): International Cichorieae Network: Cichorieae Portal. Published on the internet at http://wp6-cichorieae.e-taxonomy.eu/portal/; accessed 6/3/2010.
- Marshall, J.B., 1962. Notes on British Crepis. 1. Introduction and key., Bot. Soc. Brit. Isles Proc., 4(4) p.398-403
- McCallum Webster, M. 1978. Flora of Moray, Nairn & East Inverness. Aberdeen University Press. Aberdeen.
- Ross-Craig, S. 1962. Drawings of British Plants XV11 Compositae (3). G. Bell & Sons Ltd. London.
- Silverside, A.J. 1990. Dandelions and their allies. In A guide to some difficult plants. Wild Flower Society. Swan, G.A. 1993. Flora of Northumberland. The Natural History Society of Northumbria.
- Swan, G.A., Swan, M., 1962. The Soft Hawk's-beard (Crepis mollis Aschers.) in Northumberland, Vasculum, 47 p.28-29.
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