Cephalanthera damasonium

Description

Cephalanthera damasonium, the white helleborine, is a species of orchid. It is widespread across much of Europe, the Middle East and Asia. Cephalanthera damasonium is the type species of the genus Cephalanthera. Cephalanthera damasonium is a herbaceous plant, reaching a maximum height of about 60 cm. Leaves are ovate, becoming narrower higher up the stem, with parallel venation. It has white flowers which never fully open. Each shoot can carry up to 16 flowers. Across its range this species flowers May–June. It is a perennial species which tends not to spread vegetatively. This species is differentiated from the similar and closely related Cephalanthera longifolia, by comparing the leaves. The rarer Cephalanthera longifolia has longer, narrower leaves. Found in shady lowland forest with little undergrowth, especially under beech trees, occasionally spreads onto chalk scrub. Can colonise new beech forest quite quickly. Requires a well-drained soil above chalk or oolitic limestone. This species is found in Europe from England and Sweden to Russia and Iran; also Bhutan, India, Myanmar and Yunnan. The flowers of this species hardly open, because they are autogamous (self-pollinating). Before anthesis, the opening of the flower, the anther opens and the pollinia directly sink onto the stigmatic surface. Then pollen tubes start growing. This pollination mode enables the white helleborine to grow in deep shade, where the pollinators are almost absent. Cephalanthera damasonium has been indicated to be a mycorrhizal generalist. A 2017 investigation found that in Italy mycorrhizal associations are formed with Agaricomycetes, Ascomycota, Cadaphora luteo-olivacea, Cenococcum geophilum, Ceratobasidium including C. cornigerum, Cryptococcus carnescens, Exophiala salmonis, Hymenogastraceae including Hymenogaser cytrinus and H. bulliardii., Pezizomycetes, Sebacina sp. and Tetracladium furcatum. It has been suggested that the presence of this orchid species in a woodland is an indicator that edible truffles can be found there, but this is not always the case.