Epipactis Youngiana A.J.Richards & A.F
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Epipactis youngiana A.J.Richards & A.F. Porter Young’s Helleborine ORCHIDACEAE SYN.: Epipactis helleborine var. youngiana (Richard & Porter) Kreutz (2004) Status Schedule 8 Wildlife & Countryside Act UK BAP Priority Species since 1995 (1981) Lead partner: Plantlife International Status in Europe: British endemic 9 10km squares post 1987 UK Biodiversity Action Plan There is one current target following the 2001 Targets Review: T1- Maintain a minimum of seven populations across its range (revised). Progress on targets as reported in the UKBAP 2002 reporting round can be viewed at: http://www.ukbap.org.uk/2002OnlineReport/mainframe.htm The full Action Plan for Epipactis youngiana can be viewed online at: http://www.ukbap.org.uk/UKPlans.aspx?ID=285 Contents 1 Morphology, Identification, Taxonomy and Genetics ...........................................2 1.1 Morphology and Identification...................................................................2 1.2 Taxonomic Considerations........................................................................3 1.3 Genetic Implications................................................................................5 2 Distribution and Current Status .......................................................................5 2.1 United Kingdom......................................................................................5 2.1.1 England ..........................................................................................6 2.1.2 Scotland .........................................................................................7 2.1.3 Wales .............................................................................................8 3 Ecology and Life Cycle.....................................................................................9 4 Habitat Requirements ................................................................................... 10 4.1 History and Importance of Human Activity................................................ 10 4.2 Communities and Vegetation .................................................................. 10 4.3 Future Prospects................................................................................... 11 5 Management Implications .............................................................................. 11 6 Threats/Factors Leading to Loss or Decline, or Limiting Recovery ........................ 12 Work on Epipactis youngiana is supported by: 1 7 Current Conservation Measures ...................................................................... 12 7.1 In Situ Measures................................................................................... 13 7.2 Ex Situ Measures .................................................................................. 13 7.3 Research Data...................................................................................... 13 7.4 Monitoring ........................................................................................... 13 7.5 Recommendations for Future Work.......................................................... 13 8 References .................................................................................................. 14 9 Acknowledgements ....................................................................................... 15 10 Contacts ................................................................................................. 15 11 Links ...................................................................................................... 15 1 Morphology, Identification, Taxonomy and Genetics 1.1 MORPHOLOGY AND IDENTIFICATION Epipactis youngiana is a perennial orchidaceous herb, 15-40 cm high when in flower. Epipactis is an easily identified genus, and the following characters help to distinguish this variety. Stems usually solitary, sometimes 2-3 together, typically less robust than E. helleborine (Broad-leaved Helleborine), shortly and sparsely pubescent above or glabrescent, green. Leaves more or less two-ranked, pale green, somewhat flaccid, not markedly ribbed, with an undulate margin and subacute apex. Basal leaf at least 1.2 x longer than broad, flaccid, not cucullate. Lower bracts exceeding flowers, usually less than 6 mm wide. Flowers slightly declined, rather box-shaped, 8-11 mm diameter, whitish to pale green, or in good light a clear rose-pink; hypochile purple, epichile whitish, somewhat recurved with two inconspicuous bosses. Stigma tricornute, the rostellum acute and more or less equaling the subsessile anther, producing a usually evanescent viscidium which has usually disappeared by the 4th open flower from the top; pollinia crumbling and disintegrating by day two, not often dispersed intact. Ovary pear-shaped, rather shiny, slightly ribbed, with sparse, rather prickly, stout-based hairs, becoming glabrescent. Seeds 0.9-1.3 mm in length. 2 Figure 1 - Epipactis youngiana (© Bob Gibbons/Plantlife International). 1.2 TAXONOMIC CONSIDERATIONS Epipactis youngiana is part of the E. helleborine (Broad-leaved Helleborine) complex. The latter is a common and widespread outcrossing species throughout temperate Eurasia and introduced in North America (Squirrell et al 2001). E. helleborine is exceptionally variable, often varying strikingly within populations for color, robustness, indumentum and leaf shape. At least some of this variation may be attributable to developmental or environmental conditions, so that young or stressed plants often have yellowish, rather narrow, two-ranked leaves and pale flowers. This may equally affect E. youngiana plants. Nevertheless, this complex has produced many distinctive local variants, some of which have been recognized taxonomically. Some of these are outcrossing but geographically or ecologically distinct, such as E. tremolsii from the western Mediterranean, E. helleborine subsp. neerlandica from sand-dunes on Channel and North Sea coasts, E. distans from the Alps, E. latina from Italy, and E. condensata from the eastern Mediterranean (there are others; there is an account in full in Delforge 1995). E. helleborine subsp. neerlandica and its autogamous derivative E. renzii are morphologically distinct but cannot readily be separated from E. helleborine by molecular characters and are now often treated as varieties (Ehler & Pedersen 2000, Pedersen & Ehler 2000). Other taxa within the E. helleborine complex have evolved partial or complete autogamy through early pollinium disintegration while still in the anther and the absence of a viscidium on the rostellum (or its early disappearance); this syndrome is often 3 accompanied by small pendant flowers which sometimes do not open fully (Richards 1982). In western and central Europe, E. dunensis, E. leptochila and E. muelleri are distinctive, invariable, local autogamous taxa of this type and there are several more in the Balkans. Harris (1993) and Harris & Abbott (1997) follow Richards & Swan (1976) in calling this inland taxon ‘E. leptochila’. Squirrell et al (2002) clearly establish that the correct name for these populations is E. dunensis. Epipactis youngiana was first detected in Northumberland by the late Tony Porter in 1975, and published in 1982 (Richards & Porter 1982). At that time it was known from four sites in that county. In the early 1980’s, very similar plants were discovered from central Scotland, associated with birch woodland colonizing bings (industrial spoil). The distinctive features of the variety are listed above, but it should be noted that it usually occurs with E. helleborine (as do other rare Epipactis species) and care must be taken not to confuse it with depauperate individuals of the latter. Table 1 summarizes the most reliable characters for E. youngiana, as compared to E. helleborine. Table 1 - Comparison of E. youngiana characteristics with E. helleborine. EPIPACTIS YOUNGIANA EPIPACTIS HELLEBORINE Basal leaf >1.2 as long as broad Basal leaf <1.1, usually <1.0 as long as broad Basal leaf flat, flaccid, unribbed, silky to Basal leaf cucullate, stiff, ribbed, coarse to touch, margins undulate touch, margins not undulate If flowers colored, clear pink Flowers with a ‘dirty’ suffusion of pink Rostellum nearly equaling anther Rostellum not more than half-way on anther Ovary shiny with sparse ‘prickly’ hairs Ovary matt, sparsely pubescent to glabrous It was originally considered that E. youngiana was probably hybridogenous in origin, with E. helleborine as one parent and an autogamous species as the other, and that an autogamous mating system had ‘fixed’ distinctive hybridogenous features. It was noted that certain habitats in which it occurred were man-made and kept free from competition by physical and chemical features, inviting the suggestion that human activity had unwittingly brought the parental species into contact, and that the hybridogenous taxon which had thus arisen favored certain man-made conditions. Subsequent work, notably by Harris & Abbott (1997) and Hollingsworth et al (in press) has clarified certain points. E. youngiana is very closely related to E. helleborine, and English populations at least of the former variety probably originate from local populations of E. helleborine. E. phyllanthes (Green-flowered Helleborine) is definitely not a parent to E. youngiana, although E. dunensis (Dune Helleborine), which occurs in both the main districts where E. youngiana is found, could have been (as a male parent). Although observations suggest that E. youngiana must receive a substantial proportion of self pollen, it possesses the population