Holly Leaved Naiad

Occurs as either an annual or a short-lived perennial, and flowers in July and August (1). Male plants were only recently discovered in the UK, it was previously thought that the plant could reproduce without cross-fertilisation (1).

Holly-leaved naiad is a UK Biodiversity Action Plan priority species. The Species Action Plan produced to guide the conservation of the species aims to maintain the current populations, and restore the plant to at least five adjoining waterways before the year 2004 (2). All three of the known sites are Sites of Special Scientific Interest (SSSIs), and the Royal Botanic Gardens, Kew are investigating seed-storage techniques suitable for the species (2).

Holly-leaved naiad is an aquatic plant (1) that has tough narrow leaves on forked, brittle stems. Both the leaves and the stems have spiky projections; these occur particularly towards the tip of the stem (3). The flowers are highly inconspicuous, and the fruit, which lacks a stalk, is fleshy (5).

Prefers clear unpolluted water in fens and reedbeds (2), and shows a preference for sheltered areas (1). It typically grows at depths of between 0.5 and 1.5m (1) often in slightly brackish water (5).

This species is found in the UK in just three of the Norfolk Broads (2). It is also known from both temperate and tropical areas including Europe, Asia, Australia, Africa, and North and Central America. (1). In Europe the species is classified as Vulnerable (1).

Classified as Vulnerable in Great Britain, and is fully protected in the UK by Schedule 8 of the Wildlife and Countryside Act 1981 (1).

Main threats to the species include nutrient enrichment of water bodies following sewage inputs and agricultural run-off, and boat traffic, which causes pollution and turbulence (2).