Biological Flora of Britain and Ireland: <i>Hammarbya paludosa</i>

1. This account presents information on all aspects of the biology of Hammarbya paludosa (L.) Kuntze (bog orchid, bog adder's-mouth orchid) (Malaxis paludosa (L.) Sw., Ophrys paludosa L.), 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, floral and seed characters, herbivores and disease, history, and conservation.2. Hammarbya paludosa is a small bisexual perennial forb. It occurs in open habitats in bogs, mires and heaths as well as semi-shaded open woodland and, in some areas, in shaded coniferous forest. It is found in a few locations in the southern England (the New Forest, Dorset, Devon and Cornwall), in Cumbria and Northumberland, and in western counties in Wales. It is rare in Ireland but wide spread but very local in Scotland. H. paludosa has a Holarctic circumboreal range. Ninety per cent of known locations are recorded in Northern Europe and the British Isles.3. Hammarbya paludosa occurs on Sphagnum, other mosses and bare peat, overlying a variety of superficial deposits and sedimentary, metamorphic and igneous rocks. The pH of the rooting substrates ranges from acidic to neutral and slightly alkaline. Its nutrient status is oligotrophic, although occasionally mesotrophic, and very rarely eutrophic. It grows well in conditions of consistent lateral flow of water in the substratum.4. Hammarbya paludosay is visited by small insects of the order Diptera. Two species of gnats are recorded as orchid pollinators: Phronia digitata and Sciara thomae. It produces a small amount of nectar but is often considered as non-rewarding. The seeds are dust-like, dispersed by wind and water and the species has a short-term seed bank. Tiny bulbils (propagules) are formed on the leaf margins. They are dispersed by water.5. Hammarbya paludosa has declined in Britain since the late 19th Century primarily due to drainage of its mire habitats in lowland regions of southern and eastern England and Wales. The decline slowed down by the 2000s, and new locations have been found in Scotland and Ireland

Recent observations of "mystery star jelly" in Scotland appear to confirm one origin as spawn jelly from frogs or toads

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