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Stellaria palustris

Taxonomy 

Name: Stellaria palustris Retz.

Common name: Marsh Stitchwort.

Synonyms

  • S. dilleniana Moench, non Leers
  • S. glauca With.
  • S. parviflora (Kl. & Richt) Druce.

Fl. Nordica finds the species very variable, giving six ‘entities’, though raising none to even varietal status, separating on height, habit, degree of branching, length of internodes and branches, leaf texture, density of inflorescence and flower size. Hybrids – none known in BI but with S. graminea in Fl. Nordica.

Chromosome No.: 2n = c.130 (Clapham, Tutin & Moore 1987; Stace 2010); 2n =182, 10- to 14-ploid (Fl. Nordica).

Stellaria palustrisStellaria palustris

Photography: R. Stokes

Identification 

The flowers are intermediate between S. holostea and S. graminea. It differs from the former by the leaves being waxier, with petals cleft to the base and three-veined sepals, and from the latter by the glabrous bracts and sepals, and by its greyness rather than greenness. Apart from the usually distinctive colour of the aerial parts, S. palustris grows up to a height of around 60 cm and has larger flowers than S. graminea, the only species with which it might possibly be confused, although the latter prefers better drained soils. Walters (1985) draws attention to a green (rather than glaucous) variant that occurs at Woodwalton Fen and possibly elsewhere, and may well be overlooked.

Distribution 

Widespread in eastern and southern England, as well as central Ireland, but rare in Scotland and Wales. As a member of the European Boreo-temperate element, it is quite widespread in northern Europe, eastwards to Russia, and extending southwards at least to the Alps and the Carpathians, but very uncommon south of these. Widely naturalised outside its native range (Hultén & Fries 1986; Jalas & Suominen 1972-1999).

BSBI Hectad Map 

Click on the map to view full-size on the BSBI Maps Scheme website.

Status 
  • Origin: native.
  • Rarity: although it does not qualify as Nationally Scarce, it is found in only 2.28 tetrads per hectad in a sample of 19 recent tetrad floras - considerably lower than its hectad distribution would imply (Pearman, in press).
  • Threat: it has suffered a marked decline (Change Index -0.89). Many sites were lost in C. & E. England before 1930, and losses have continued in most parts of its British range. However, some recent floras, based on recent work (Norfolk, Somerset) rather than on surveys over many years (Hampshire, Oxford), give no particular hint of decline, merely stating that it is always an uncommon plant. In other apparent centres (Cambs, Hants, Suffolk, Surrey and Berks) the most recent Floras also describe it as rare and decreasing. There are many recent records from Ireland, but we have little idea of its frequency below hectad level, or the trend there, other than in Co. Fermanagh, where the draft forthcoming Flora states that although frequent in its core area, at several of the outlying stations recorded in the 1950s or earlier, it seems to have disappeared, as there are no post-1975 records for them.
  • Conservation: most county recorders list it as an axiophyte.
Ecology 

A species of damp and wet places, including pastures, grassy fens and marshes, especially in areas with standing water in winter. This is provided in fens, meadows, pastures and scrub, primarily around the larger lakes, but occasionally also by rivers, streams and ditches. It is also able to colonise artificial habitats such as old peat diggings. It is included in the following NVC communities: M22 Juncus subnodulosus fen-meadow, S24 Phragmites australis fen and S27 Carex rostrata tall-herb fen (Rodwell 1991, 1995).

Further Work 

The vegetation communities listed for it in Rodwell (1991-2000) seem insufficient, possibly because, as a fairly rare plant, it was found in few samples. A dedicated study of its vegetation and habitats might therefore provide useful insights into its ecology and conservation. Taxonomically, it seems a little unstable. Subspecies and/or varieties might be worthy of further investigation, and the range of chromosome counts published for it suggest that there are various ploidy levels. To be more certain about any threat it faces in Britain, we need more detailed studies of its distribution and abundance within sites. It also appears to be under-recorded at the hectad scale, to judge from the Maps Scheme maps.

References 
  • Walters, S.M. 1985. Stellaria palustris - a declining, or an overlooked species? Nature in Cambridgeshire.
Citation 
Pearman, D.A. (date accessed). Species account: Stellaria palustris. Botanical Society of the British Isles, www.bsbi.org.uk.

Orobanche rapum-genistae

Taxonomy 

Greater Broomrape, Orobanche rapum-genistae Thuill. (O. major auct.) is one of the most straightforward of the broomrapes. For a review of the taxonomy and identification of Orobanche in Britain, refer to Rumsey & Jury (1991).

Chromosome No.: 2n = 38 (Stace 2010).

Orobanche rapum-genistae

Photography: A.J.Lockton

Distribution 

There have been thought- provoking accounts by Mike Foley in Scarce Plants (Stewart, Pearman & Preston 1994) and the New Atlas (Preston, Pearman & Dines 2002) in which he makes predictions about changes in the distribution of this species. As time goes by these theories can be tested as more data comes in. The maps in Scarce Plants were ground-breaking for the time, giving different distributions based on the recording periods used. Unfortunately, the technique that was employed is open to some doubt because the date periods are not comparable. One map shows all records, which accounts for 300+ years of recording, while another shows less than 14 years of recording for the 1980+ map. It is no wonder that a decline was detected. Bowen’s detailed account of it in Fl. Dorset (2000) illustrates the problem rather nicely. Roughly speaking, there has been one record of it in Dorset every decade for the last 200 years, meaning that 22 sites have been lost while only one remains. But he presents no evidence that there was ever a time when it was significantly more common than it is now.

For the Maps Scheme, we have tried to make the date classes more comparable, but with a species as noticeable and reliably recorded as this one, there is still undoubtedly some bias. What is needed is a detailed compilation of all records, giving the most accurate dates possible, to demonstrate conclusively that it is not simply an intermittent or mobile species. Many county recorders are currently making efforts to improve the quality of the early records, and questions such as this demonstrate the importance of such work. It is clear that there has been almost no change in the range of O. rapum-genistae, although it may have become more sparsely scattered within its area. Foley (op. cit.) has speculated that it may have retreated to coastal areas and that its decline may be climate-related; but these observations do not appear to be supported by recent records. An alternative theory could be that habitat loss is the main cause of any change or decline.

BSBI Hectad Map 

Click on the map to view full-size on the BSBI Maps Scheme website.

Ecology 

It is clear that there has been little change in the range of O. rapum- genistae, although it may have become more sparsely scattered within its area. In Scarce Plants Foley speculated that it may have retreated to coastal areas and that its decline may be climate-related; but these observations do not appear to be supported by recent records. An alternative theory could be that habitat loss is the main cause of any change or decline. O. rapum-genistae is a plant of scrubby grassland. It is difficult to find much ecological information on it - possibly because it is rare in most counties. I have seee it in U1 Festuca ovina grassland that is going over to W23 Ulex europaeus-Rubus fruticosus scrub and, ultimately, W10 Quercus robur woodland; but I have also seen it in other vegetation such as MG1 Arrhenatherum elatius grassland, perhaps. If the grassland is agriculturally improved, the scrub is cleared, or the woodland allowed to develop too far, the O. rapum-genistae disappears. Whether this sequence is typical or not, I do not know; Rodwell (1991-2000) lists no NVC communities for it.

How long O. rapum-genistae can persist at a site is a question that is in need of further investigation. Foley reports, in Scarce Plants, that it reappeared after the great storm of 1987 made clearings in some woods in southern England. In one site in Shropshire it was refound 87 years after the previous record (Shropshire Botanical Society Newsletter No. 16 (2007)) and Rumsey & Jury (1991) showed that it had persisted in one site in Lincolnshire for nearly 100 years. This suggests a ‘strategy’ of persisting in a vegetative state or in the seed bank until suitable conditions return; but, alternatively, it may simply be a good coloniser.

Further Work 

How big are the populations? Several authors state that populations are often small. This may be true, but large populations occur as well. At Old Oswestry there were some 200 flowering spikes in 2007, and Martin Rand reported 710 spikes at Summerlug Hill in 2004. Details of population size would be worth collecting, because this is clearly a plant with a risky lifestyle. Being parasitic upon a host that occurs in a transitional habitat, and killing that very host after a few years, means that there isn’t much opportunity to make long-term plans. Each plant produces thousands of seeds, and a large population must produce millions. Are these widely dispersed or do they build up a persistent seed bank?

References 
  • Bowen, H. 2000. The Flora of Dorset. Pisces Publications, Berkshire. Rumsey, F.J. & Jury, S.L. 1991. An account of Orobanche L. in Britain and Ireland. Watsonia 18, 257-295.
Citation 
Lockton, A.J. (date accessed). Species account: Orobanche rapum-genistae. Botanical Society of the British Isles, www.bsbi.org.uk.

Leucojum aestivum

Taxonomy 

Leucojum aestivum (L.), Summer Snowflake, has enjoyed a stable taxononomic status, but in 1910 it was merged with L. pulchellum (Salisb.) creating two subspecies:

  • L. aestivum subsp. aestivum
  • L. aestivum subsp. pulchellum (Salisb.) Briq.

 

The name Leucojum is derived from the Greek for ‘white violet.’

Several non-UK native members of the genus were split into a new genus, Acis, recently after genetic results showed greater differences than between Leucojum and Galanthus.

Common names: Summer Snowflake; Loddon Lily (strictly only subsp. aestivum).

Chromosome No. 2n = 22 (Stace 2010) in both subspecies.

Leucojum aestivum

Photography: J.R. Crellin

Identification 

Leucojum is a genus in the Amaryllidoidae sub-family of the Liliaceae. These are bulbous plants with narrow leaves rising from the base of the plant. Flowers are solitary or in an umbel with a spathe at the base. The ovary is inferior. There is one stigma with a simple or three-lobed style. Some have a funnel-shaped corona within the tepals. Leucojum species have few or solitary flowers with all six tepals similar, hanging as a bell. Tepals are white with green or yellow patches. There is no corona. By contrast, Galanthus spp. (snowdrops) are distinguished by the inner three tepals forming a distinct bowl-shaped structure.

Differences between the two subspecies:

ssp. aestivum;

  • No. of flowers (2-)3-5(-7)
  • Tepals larger: 13-22 mm
  • Spathe (bract behind flowers on stem) wide: 7-11 mm.
  • Flower stem edges rough - stems with the two sharp edges remotely and often inconspicuously denticulate, at least in lower half (Stace 1997).
  •  

ssp. pulchellum;

  • Flowers (1-)2-4
  • Tepals smaller: 10-15 mm
  • Spathe narrow: 4-7 mm
  • Stem edges smooth (‘entire throughout’)
  • (In practical fieldwork the distinction is easily made by gently running the fingers along the stem edges.)

 

Leucojum aestivum ssp. aestivumLeucojum aestivum ssp. pulchellum

ssp. aestivum                                                 ssp. pulchellum

Photography: J.R. Crellin

Distribution 

Both sub-species may be found as escapes from cultivation but the more frequent sub-species in cultivation is L. aestivum subsp. pulchellum. L. aestivum subsp. aestivum occurs in Ireland, The United Kingdom, Netherlands, Belgium, Germany, France, Switzerland, Italy, Austria, Yugoslavia, Albania, Greece, Czech Republic, Slovakia, Hungary, Romania, Bulgaria, Ukraine (SW and the Crimea), Turkey, Iran, Georgia, Russia (the Caucasus) (Fl. Europaea). L. aestivum subsp. pulchellum is native to France (the Alps-Maritimes, Corsica), Spain (Balearic Islands), Italy (continent, Sardinia) (Fl. Europaea).

BSBI Hectad Map 

Click on the map to view full-size on the BSBI Maps Scheme website.

Leucojum aestivum

Leucojum aestivum ssp. aestivum

Leucojum aestivum ssp. pulchellum

Status 
  • Origin: L. aestivum subsp. aestivum is often considered native in some parts of the British Isles (Preston, Pearman & Dines 2002), but some botanists consider this to be rather dubious.
  • Rarity: neither subspecies is rare in Britain, although ssp. pulchellum appears to be rare in Ireland.
  • Threat: Leucojum aestivum is listed as ‘Least Concern’ in Cheffings & Farrell (2005), and in the New Atlas it is given a Change Index of +2.42, which shows a significant increase.
  • Conservation: The counties of Berkshire, Dorset and Co. Waterford all have Leucojum aestivum listed as an axiophyte, which means that the county recorders consider it to be indicative of good quality habitat.
Ecology 

L. aestivum subsp. aestivum occurs in wet meadows and Willow / Alder scrub by rivers in southern England north to Oxfordshire. L. aestivum subsp. pulchellum has become established in scattered communities (usually near water) through the British Isles from the Channel Isles north to Scotland but concentrated in the South of Britain and East Anglia. Neither is represented in the National Vegetation Classification.

Further Work 

The subspecies are often undifferentiated in records but are easy to distinguish once one has encountered each form. Recorders should be encouraged to make the distinction and to note any unusual habitat - particularly cases of long-established communities far from water. (The plant will survive well in drier condition in gardens - and can be seen at the top of a mound at Kew. It may be that water is more significant as a seed distribution medium than anything else.) The supposed origin of British plants creates a curious dilemma. If there really is a small native population centred on central southern England, then it should be considered Nationally Scarce, and of considerable conservation importance. However, the lack of any such status reveals the lack of confidence botanists feel in this assessment. A study of its nativity and, if it is to be considered native, its ecology in the wild, is urgently required. However, a non-native species that is increasing could just as easily be an axiophyte, if it tends to grow in good habitat and does not cause any harm. Such an understanding would be more sophisticated than the simplistic ‘native is good, alien is bad’ philosophy of the popular press.

Citation 
Crellin, J.R. (Date accessed). Species account: Leucojum aestivum. Botanical Society of the British Isles, www.bsbi.org.uk.

Crepis mollis

Taxonomy 

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).

Crepis mollis

Photography: K.J. Walker

Identification 

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.

Distribution 

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).

BSBI Hectad Map 

Click on the map to view full-size on the BSBI Maps Scheme website.

Status 
  • 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.
Ecology 

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.

Further Work 

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.

References 
  • 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.
Citation 
O’Reilly, J. 2010. Species account: Crepis mollis. Botanical Society of the British Isles, www.bsbi.org.uk.

Astragalus danicus

Taxonomy 

Astragalus danicus Retz., Purple Milk-vetch, was so named because it was thought to increase the milk yield of livestock. Synonyms include A. hypoglottis.

Chromosome No.: 2n = 16 (Stace 2010).

Astragalus danicus

Photograph by K.J. Walker

Distribution 

It is locally abundant in the British Isles. In southern and eastern England populations are confined to chalk and limestone in the Cotswolds, Salisbury Plain, the Chilterns and the Breckland region of East Anglia. It is absent from the chalk south of London and, like Pulsatilla vulgaris and Tephroseris integrifolia, this may represent a limited southerly migration since the last ice age (Rose 1957). It extends along the limestone as far north as the Yorkshire Wolds in v.c. 61. Populations further north are mainly coastal, extending from County Durham to the Moray Firth, with western outliers on cliff-tops on Tiree (Hebrides), the north coast of the Solway Firth and the Isle of Man. Inland populations occur on basalts in Northumberland and on mica-schists up to 710 m in Perthshire. There are also somewhat puzzling populations on the Aran Islands, Western Ireland. Scottish populations are the most northerly and Irish populations the westerly in Europe. All belong to subsp. danicus which is replaced by subsp. dasyglottis throughout Eastern Siberia and North America.

BSBI Hectad Map 

Click on the map to view full-size on the BSBI Maps Scheme website.

Status 

A vulnerable Red Data List species added to the list of UK Biodiversity Action Plan priority species in 2007; not previously listed as threatened, although it has probably been declining since at least the start of enclosure in the 18th century. In 1860 the Cambridgeshire botanist Charles Babington noted that ‘until recently (within 60 years) most of the chalk district was open and covered with a beautiful coating of turf, profusely decorated with Anemone Pulsatilla [Pulsatilla vulgaris], Astragalus Hypoglottis [A. danicus], and other interesting plants. It is now converted into arable land, and its peculiar plants mostly confined to small waste spots by road-sides, pits, and the very few banks which are too steep for the plough’ (Babington 1860). It appears to have declined substantially on the chalk in S. England and limestone in N.E. England since then, largely due to agricultural improvement or lack of grazing. Less is known about populations in Scotland and Ireland which are presumably stable.

Ecology 

A low-growing perennial of dry, infertile grassland. Like many British calcicoles it appears to be physically rather than chemically restricted and is equally happy growing on moderately acid sands/gravels (e.g. dunes) as long as competition from other species is low. It grows best at low altitudes in short calcareous grassland on lime-rich soils. This includes open rides in conifer woodland in Norfolk and in the very short turf of firing ranges on Salisbury Plain.

In northern England, Scotland and the Isle of Man it occurs in grassland associated with base-rich rock outcrops, cliff-tops and sand dunes. In Scotland, for example, it grows on Old Red Sandstone sea-cliffs and on mica-schist. Populations on the Aan Islands in Western Ireland occur on deposits over limestone pavement.

Little is known about its regenerative ecology. However, the recolonisation of former plantation sites in Breckland suggests that its seedbank may be long-lived (A. Byfield, pers. comm.). A. danicus occurs in a range of NVC communities. Populations on calcareous sands and gravels in Breckland are confined to short Festuca ovina grasslands (CG2/7), especially Cladonia spp. sub-community CG7b as well as inland stands of Festuca rubra-Galium verum fixed dune grassland (SD8). Chalk populations occur in short, species-rich Bromopsis erectus (CG3) grassland (as on Newmarket Heath, Cambridgeshire). On Jurassic limestone, as at Barnack Hills and Holes in Northamptonshire, it occurs in Brachypodium pinnatum- Bromopsis erectus grassland (CG5). Inland and coastal populations in northern England and Scotland are less well studied although populations have been recorded amongst inland stands of Festuca rubra-Armeria maritima maritime grassland (MC8).

Astragalus danicus - white form

Photograph by K.J. Walker

Further Work 

There is an urgent need to assess the scale and causes of the decline in S.E. England, where it appears to be most threatened, along with many other ‘low growing species’ dependent on open conditions. Further work on its regenerative ecology would also help inform the management needed to restore populations that have been in long-term decline.

References 
  • Babington, C.C. 1860. Flora of Cambridgeshire. J. van Voorst, London.
  • Rose, F. 1957. The importance of the study of disjunct distribution to progress in understanding the British flora. In J.E. Lousley (ed.) Progress in the Study of the British Flora, pp. 61-78. Botanical Society of the British Isles, London.
Citation 
Walker, K.J. (Date accessed). Species account: Astragalus danicus. Botanical Society of the British Isles, www.bsbi.org.uk.

Ophrys insectifera

Taxonomy 

Ophrys insectifera L., Fly Orchid, is uncontroversial, even within the polymorphic Ophrys genus.

 

Synonyms:

  • O. muscifera Huds.
  • O. myodes Jacq.

There are very rare records of hybrids with O. apifera (N. Somerset and W. Sussex) and with O. sphegodes (E. Kent).

 

Chromosome No.: 2n = 36 (Stace 2010). 

Ophrys insectifera

Photograph by K.J. Walker

Identification 

Taller, more slender than the other members of the genus found in Britain and Ireland, with a distinctive blue patch across the narrow lip. The leaves differ from O. apifera in being shiny rather than waxy.

Distribution 

Widespread only in the south and south east of England, with well over half of the records and 60% of the recent records. Elsewhere it has been found in 40 hectads in E. Anglia (only two post 1987), in 70 hectads from Gloucs. northwards to Cumbria (c. 25 post 1987) and in 30 hectads in Ireland (with 16 of these post-1987). There are no records from Scotland, and only five from Wales.

European Temperate Element. It is widespread throughout central Europe, but with only scattered records from the Iberian Peninsular, the west Mediterranean, and southern Scandinavia east towards the Urals (Hultén & Fries 1985). As it is not as 'Mediterranean' in its climatic preference, its range extends further north than other Ophrys species (Sanford 1991).

Altitudinal range: 0-390 m (Helbeck Wood, Brough, Westmorland).

BSBI Hectad Map 

Click on the map to view full-size on the BSBI Maps Scheme website.

Status 

Origin: native.

Rarity: Scarce in Britain. Scarce in Ireland. Absent from Scotland and Northern Ireland.

Threat: Vulnerable (Cheffings & Farrell 2005). It is difficult to see a trend in the distribution. There were more records (about 90 additional 10km squares) in the New Atlas (Preston et al. 2002) than in Perring & Walters (1962), but an overall drop in hectads with recent records (c. 20) explains the reasons behind the listing as Vulnerable. However one would have to analyse each hectad to be able to say that the increase in overall recorded hectads was due to new records of old sites or new sites being found.

Conservation: added to the list of UK Biodiversity Action Plan priority species in 2007.

There is no clear pattern to the losses. Those in East Anglia and the Welsh Marches were largely before 1930, and those since are throughout the range. A study in 2004 covering Dorset, Hampshire and Sussex confirmed only small losses at a hectad level, but dramatic declines at tetrad, and even more at 1km level. A definitive map showing the number of tetrads per hectad would be a great help.

There is also no clear reason for the losses, though denser woodland, more overgrown woodland edges as well as losses to coniferisation and changes in management of quarries and verges are all reported as causes of loss. Some sites have been lost from drainage of fens. It is interesting that most of the other widespread woodland orchids, including Cephalanthera damasonium, Neottia nidus-avis and Platanthera chlorantha, are also listed on the Red List for the first time. Notes and possible resons for decline are in Edwards & Pearman (2004) and Sanford (1991). Furthermore other woodland edge plants, such as Campanula patula, Fallopia dumetorum and Melittis melissophylum have also dramatically declined, demonstrating that, in the writer’s view, this is one of the most threatened habitats in Britain.

There is anecdotal but no hard evidence for some decline in mainland Europe.

Ecology 

A shade-tolerant tuberous herb usually found on chalk and limestone soils, and, like many orchids, sporadic in its appearance. In the south of England it is usually found in open deciduous woodland and scrub, but also recorded from denser shade, especially in beech woods. In woodlands it may grow with other orchids, such as Cephalanthera damasonium, Neottia nidus-avis, Orchis mascula and Platanthera chlorantha, and is included in the NVC community W12. On wood edges it grows in CG communites.

More rarely, but increasingly further north it is found in calcareous grassland, chalk-pits, limestone pavement, disused railways, spoil heaps and, rarely, unstable coastal cliffs - reaching its northerly limit on limestone slopes scree? in Cumbria (Foley & Clarke 2005). Interestingly, Irish populations are confined to open calcareous flushes and fens (M13, M13b) very unlike its habitats in England. It still survives at least one similar site on Anglesey (Cors Bodeilio) where it grows on Schoenus tussocks within species-rich fen (I. Bonner, pers. comm.). See Roberts (1958) for details of this remarkable habitat.

 The Fly Orchid is not very slow growing but it does not easily colonise new sites. This may be partly due to low seed production (Sanford 1991). The flowers are visited by wasps but pollination is often haphazard, with as few as 20% of flowers with mature seed (Foley & Clarke 2005). Flowering often starts in May in the south, though this can continue till July, especially further north.The limitations of such a finely tuned pollination mechanism may become increased, as solitary wasps are also becoming scarce, due to habitat loss (Sanford 1991). 

Further Work 

It would be interesting to test the hypothesis that it has declined along woodland edges, by comparison with sites that were still managed in traditional ways, and it would be surprising if examples were not available.

Finer details on distribution are needed to evaluate real losses.

References 
  • Foley, M & Clarke, S. 2005. Orchids of the British Isles. Cheltenham, Griffon Press.
  • Halliday, G. 1997. A Flora of Cumbria. Centre for North-West Regional Studies, University of Lancaster.
  • Hultén, E. & Fries, M. 1986. Atlas of north European vascular plants: north of the Tropic of Cancer. 3 vols. Königstein: Koeltz Scientific Books.
  • Roberts, R.H. 1959. Notes on the fen habitat of Ophrys insectifera in Anglesey. Proceedings of the B.S.B.I. 3: 274-278.
  • Sanford, M. 1991. The orchids of Suffolk. Ipswich: Suffolk Naturalists’ Society.
Citation 
Pearman, D.A. (date accessed). Species account: Ophrys insectifera. Botanical Society of the British Isles, www.bsbi.org.uk.

Gentianella campestris

Taxonomy 

Seemingly uncontroversial, though there is much taxonomic confusion amongst the rest of the genus in the British Isles. However, some continental botanists (cf. Hultén & Fries 1986) separate our species into subsp. campestris and subsp. baltica, both with very similar ranges and both mapped as occurring here.

 

Accepted name: Gentianella campestris (L.) Börner, Field Gentian.

 

Syn: Gentiana campestris L.

 

Hybrids – none known.

 

Chromosome No.: 2n = 36 (Stace 2010). 

Gentianella campestris

Photograph: K.J. Walker

 

Identification 

Distinguished from all others in the genus by the very unequal calyx lobes – the outer much larger than the inner and enclosing them.

 

Distribution 

Gentianella campestris is widespread in Scotland, in northern England and North Wales, and in north and west Ireland, but now very rare indeed in England south of the Lake District and the adjacent Pennines.

Generally lowland, but reaching 915 m at Cairnwell (E. Perth, S. Aberdeen).

European Boreo-temperate element. It is quite widespread in northern Europe, extending southwards at least to the Alps, but more rare in the Pyrenees and the Picos de Europa.

 

BSBI Hectad Map 

Click on the map to view full-size on the BSBI Maps Scheme website.

 

Status 

A Vulnerable Red Data List species (Cheffings & Farrell 2005) added to the list of UK Biodiversity Action Plan priority species in 2007; not previously listed as threatened. G. campestris had already suffered a marked decline before 1930, but sites are still being lost through overgrazing in the uplands and the neglect of lowland pastures. In its English stronghold, Cumbria, it has disappeared from half the 10 km squares for which there are post-1930 records. It is now extremely rare in southern England, apart from in the New Forest, where it is stable and even possibly increasing; it has recently been reported from three sites on The Lizard and only one each in E. Cornwall, S. Devon, N. Hampshire, E. Sussex, W. Norfolk, Staffordshire and Derbyshire.

 

It is apparently extinct in many counties including Berkshire and Shropshire. Most of the historical losses must have been from agricultural improvement, though many of the recent losses have arisen from relaxation of grazing and invasion by heather and other shrubs. The extent to which acid grassland and heathland populations have declined as a result of atmospheric pollution is unknown but may account for at least some of the losses in S.E. England. Elsewhere in Britain and Ireland there is only evidence of local losses.

 

It is regarded as in serious decline in Scandinavia with a 90% reduction in the last 50 years (Eriksson & Kiviniemi 1999) and the West German plant atlas (Haupler & Schonfelder 1988) shows very large losses.

 

 

Ecology 

A biennial, occasionally annual, herb of mildly acidic to neutral, infertile (Ellenberg Value for N = 3), soils in a variety of open habitats, including pastures, hill grassland, grassy heaths, sand dunes, machair and road verges (Preston et al. 2002). The flowers are typically purple but sometimes white (Scott & Palmer 1987).

 

In Cornwall it grows in brown earths over serpentine, in North Hampshire on the junction of the chalk and the Reading beds, and in the New Forest on the Headon clays. On limestone it probably indicates surface leaching or the presence of non-calcareous superficial deposits (Halliday 1997). At least in Cornwall and Hampshire Carex montana grows in the same habitat. In Pembrokeshire it grows in maritime heaths overlaying Jurassic limestones.

 

In NW Scotland it is usually a an acid grassland plant, often growing on machair, fixed dunes and road verges where the drainage is sharp, though it does occur in a variety of other habitats, such as grassy sea-cliffs on granite and gabbro on Rum.

 

It is listed for the following NVC communities, CG1, CG2, CG10, CG14and MC10, but as it rarely occurs in abundance, and it was present in small quantities in a small number of quadrats collected for the NVC, these might not be particularly representative of its habitats.

 

In Local Change (Braithwaite et al. 2004) there is an interesting angle to its ecology, based on its distribution in 2 km squares throughout Britain. They found it to be a component of a calcareous upland vegetation, associated with Selaginella selaginoides. This is one of the more rapidly declining suites of species.

 

Flowers are hermaphrodite, pseudo-cleistogamous and markedly protandrous. Flowering is usually between 7-10 but can be variable especially in dry summers when populations tend to be small (Crawley 2005). The flowers are visited by humble-bees and lepidoptera, sometimes selfed (Clapham et al. 1987). In Scandinavia a decrease in populations and increasing fragmentation may have lead to a reduction in gene flow between populations and a decrease in cross-pollination within populations (Lennartsson & Oostermeijer 2001). Plants are monocarpic and regeneration is exclusively by seed. Seeds germinate in the spring but it is not known whether they have a dormancy mechanism or form a persistent seedbank.

 

Further Work 

Due to its low stature and lifecycle Gentianella campestris appears unable to persist in closed communities and probably requires frequent (micro) disturbance to create suitable conditions for regeneration (for example, plants are often confined to faint sheep/animal tracks in closed heathland). Research into these microhabitats would make an excellent project and would help us to understand why this species persists on some sites but not on other apparently suitable sites closeby.

 

Why does it appear to be flourishing in the New Forest but not elsewhere in southern Britain?

 

What are the effects of increasing atmospheric deposition of nutrients?

 

Is increasing fragmentation leading to a reduction in gene flow between and within populations?

 

Are these same factors affecting populations in the north and west?

 

What is the status of subsp. balticus?

 

Although it is still frequent in the north, it may be declining within its range - a process that is difficult to detect from 10 km maps. Detailed records collected by the Threatened Plants Project will help to monitor its status in future.

 

References 

  • Clapham, A. R., Tutin, T. G. & Moore, D. M. 1987. Flora of the British Isles, 3rd ed. Cambridge: Cambridge University Press.
  • Crawley, M.J. 2005. The Flora of Berkshire. Brambleby Books, Harpenden
  • Eriksson, O. & Kiviniemi, K. 1999. Site occupancy, recruitment and extinction thresholds in grassland plants: an experimental study. Biological Conservation 87(3):  319-325.
  • Halliday, G. 1997. A Flora of Cumbria. Centre for North-West Regional Studies, University of Lancaster.
  • Haupler, H.  & Schonfelder, P. (eds) (1988). Atlas der Farn- und Blütenpflanzen der Bundersrepublik Deutschland. Stuttgart: Eugen Ulmer.
  • Hultén, E. & Fries, M. 1986. Atlas of north European vascular plants: north of the Tropic of Cancer. 3 vols. Königstein: Koeltz Scientific Books.
  • Lennartsson, T. & Oostermeijer, J.G.B. 2001. Demographic variation and population viability in Gentianella campestris: effects of grassland management and environmental stochasticity. Journal of Ecology 89(3): 451–463.

 

Citation 
Pearman, D.A. (date accessed). Species account: Gentianella campestris. Botanical Society of the British Isles, www.bsbi.org.uk.

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