About Epipactis helleborine subsp. tremolsii (Pau) E.Klein
Epipactis helleborine can reach a maximum height of 1 meter (3 feet 3 inches) or taller when growing under good conditions. It produces broad, dull green, strongly ribbed, flat leaves. Its flowers are arranged in long, drooping racemes, with dull green sepals and shorter upper petals. The lower labellum is pale red, and much shorter than the upper petals. Achlorophyllous, white forms of Epipactis helleborine have been recorded; these achlorophyllous plants are typically shorter, and can be as small as 17 centimeters. Flowering occurs between June and September. This subspecies is widespread across much of Europe and Asia, ranging from Portugal to China, and is also found across northern Africa. In the United Kingdom, it is widespread and common in England and Wales, absent from most of Scotland, and scattered across Ireland. In North America, it is an introduced, widely naturalized species found mostly in the Northeastern United States, eastern Canada, and the Great Lakes Region, with scattered populations in other parts of the continent. In the United States, it is sometimes called the "weed orchid" or "weedy orchid", and continues to spread to new areas across the country, including Michigan, Wisconsin, and the San Francisco Bay Area. Epipactis helleborine grows in woods and hedge-banks, and often occurs not far from paths near human activity. It is one of the European orchids most likely to be found within cities, with many known sites in Glasgow, London and Moscow, for example, and is sometimes spotted beside car parks. This orchid is known for successfully colonizing human-made (anthropogenic) habitats such as parks, gardens, and roadsides. Roadside-growing individuals of this species show distinct traits, including larger plant size and greater flower production. Pollination is affected by habitat type: pollinators including Syrphidae, Culicidae, and Apidae have greater species diversity and visit flowering sites more often in anthropogenic habitats than in native habitats. Both pollinator visitation rates and the orchid's reproductive success are higher in large populations, as these are more attractive to pollinators. This orchid species is pollinated by several Hymenoptera species, particularly the common wasp, as well as other species in the genera Vespula and Dolichovespula. Its flowers release sweet nectar to attract wasps, and this nectar has an intoxicating effect on the insects. A study of nectar from eight Epipactis helleborine populations in central Europe (Lower Silesia, Poland) found naturally occurring oxycodone (and another narcotic-like opioid) present in minute amounts. Epipactis helleborine requires a mycorrhizal symbiosis to germinate successfully, and remains partially dependent on the fungal partner when mature, though it is not particularly selective about which fungal species it associates with. Fungi recorded associating with the orchid's live roots include Tuber, Helotiales, Peziza, Leptodontidium, Hydnotrya, and Wilcoxina. It has been suggested that the presence of this orchid in woodland is an indicator that edible truffles grow there, but this is not always the case.
