Biological flora of the British Isles: Orchis anthropophora (L.) All. (Aceras anthropophorum (L.) W.T. Aiton)

Abstract

Summary1. This account presents information on all aspects of the biology of Orchis anthropophora (L.) All. (Man Orchid) that are relevant to understanding its ecological characteristics and behaviour. The following topics are presented within the framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characteristics, herbivores and disease, history, and conservation.2. Orchis anthropophora is a native species in Britain, where it occurs predominantly in chalk and limestone grassland and dune grassland. It can also be found along field margins and in old abandoned chalk pits and limestone quarries, where it is usually found at the foot of slopes. It also grows on road verges and sometimes in quite dense scrub. Orchis anthropophora tolerates some shade, but it flowers most profusely in open conditions. It is a common species in the Mediterranean region.3. Orchis anthropophora is wintergreen and has leaves throughout the winter. Flowering takes place between mid‐May and mid‐June. Vegetative adult dormancy – the failure of above‐ground parts to appear in a growing season, followed by the reappearance of full‐sized photosynthetic plants in subsequent seasons – has been observed. In most cases, dormancy does not last longer than 1 year. Orchis anthropophora is long‐lived (half‐life of cohorts ranges from 4.0 to 7.8 years).4. Orchis anthropophora is not autogamous, and pollinators are required for successful pollination and fruit‐set. Flowers are predominantly pollinated by beetles and sawflies. Terpenes are the major compounds of the floral scent profile of O. anthropophora. Natural levels of fruit‐set are generally low. Recorded values are mostly <20% but reached >80% in a population in southern France.5. Orchis anthropophora hybridizes with several other species in the genus Orchis, including O. italica, O. simia, O. purpurea and O. militaris. Intergeneric hybrids have been reported with Barlia, Dactylorhiza and Neotinea. In Britain, hybrids with O. simia and O. purpurea have been reported.6. Orchis anthropophora has declined markedly in Britain during the last century, and at present, it is rare and classified as endangered. Very few new populations are becoming established, and many populations have become extinct, mainly because of agricultural intensification (ploughing and fertilization of old fields). Conservation of the remaining populations requires moderate grazing by sheep to maintain a short turf and to promote seedling recruitment.