Biological flora of Britain and Ireland:Neottia nidus‐avis

Abstract

AbstractThis account provides information on all aspects of the biology ofNeottia nidus‐avis(L.) Rich. (Bird's‐nest Orchid) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of Britain and Ireland: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, reproductive characteristics, herbivory, history and conservation.Neottia nidus‐avisis a native mycoheterotrophic orchid; it is found most frequently in the deep humus of densely shaded beech woodlands, on limestone or chalky soils in the British Isles. The species extends throughout temperate Eurasia.Neottia nidus‐avisis a perennial, mostly monocarpic herb with mixed mode of reproduction and many adaptations to autogamy. The perennating organ is a short rhizome; vegetative reproduction by rhizome branching or root‐sprouting is rather infrequent. Because of its achlorophyllous nature,N. nidus‐avisis entirely dependent on its mycorrhizal basidiomycetes from the family Sebacinaceae for nutrition.Plastid genome ofN. nidus‐avishas been reduced as a result of the relaxation of functional constraints on photosynthesis as in other mycoheterotrophic plants. Despite this, the plant has retained all enzymes to produce chlorophyll as well as some photoprotective metabolites, such as zeaxanthin and tocopherol, whose function in the mycoheterotrophic plant remains unresolved.The species flowers from May to June, depending on latitude and altitude. The flowers emit a sweet scent and produce little nectar. They may be pollinated by flies, crawling thrips and ants but self‐pollination is presumed to be the main mode of reproduction. Between 75% and 97% of open flowers set fruits.Neottia nidus‐avisis classified asVulnerablein Great Britain. The species is scattered throughout much of the British Isles, but it is very scarce except in southern England, where it is locally abundant. The main threats are deforestation, changes in woodland management and coniferization.