Biological Flora of the British Isles: Orchis mascula (L.) L

1. This account presents information on all aspects of the biology of Orchis mascula (L.) L. (early purple orchid) relevant to understanding its ecological characteristics and behaviour. The main 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 mascula is a native herb of the British flora. It is mostly found in woodland, copses, grasslands and open pastures, mostly on neutral or base-rich soils. It can also occur in hedgerows, scrub, on roadsides and railway banks, in grikes on limestone pavement and on moist cliff ledges. It is absent from very acid or very wet sites. It tolerates a sparse to moderately dense canopy, but it does not flower in deep shade. 3. Orchis mascula is a non-bulbous geophyte with little or no capacity for vegetative spread. The main perennating organ is a tuber (strictly a rootstem tuber). In most years the tuber generates a rosette of expanded leaves, and, at the end of every year of the plant's life, the tuber is replaced by at least one new tuber. Dormancy, the failure of above-ground parts to appear in a growing season, and the subsequent reappearance of full-sized photosynthetic plants in subsequent seasons, has been observed, but does not last longer than 1 year. The species is long-lived: it takes at least 4 years from first appearance above-ground to achieve flowering for the first time. The maximum recorded lifetime after first appearance is 13 years. 4. Orchis mascula is not autogamous and pollinators are necessary for successful pollination and fruit set. Flowers are nectarless, and pollinated by deceit, mainly by bumblebees and solitary bees. Natural levels of fruit set are usually < 20%. Hand-pollination can increase fruit set to approximately 80%, indicating that seed production is strongly pollen-limited. The lowest four flowers are more likely to be pollinated than the upper flowers, probably because pollinators learn to avoid the species after discovering that it offers no reward. 5. As in most other European countries, Orchis mascula has declined in the British Isles, although it is not at threat of extinction at a national level. Most sites from which it has been lost are in central England and Scotland. Most losses have been caused by woodland clearance and coniferization, intensification of grassland management and ploughing. The cessation of traditional coppicing practises has also led to a decline in the abundance of O. mascula. Since the species is slow to colonize new forest stands or grasslands, management should focus mainly on conservation of ancient forest habitats and grasslands in which fertility is moderate to low and grazing is absent or low in intensity. Restoration of traditional coppicing practices could also lead to higher chances of the species flowering and surviving in the long-term.