Floating Aquatics
What are they?
This page includes a group of unrelated plants but they are all species that can be found floating on the water surface. Some are entirely free-floating, while others are rooted in the substrate beneath the water but have floating leaves and flowers.
Water-lilies - Nymphaeaceae
European White Water-lily Nymphaea albaNative in the UK but only known from the Isles of Scilly as an introduction on Tresco. Flowers June to August. Flowers typically white, but occasionally pink-tinted, especially on the outer petals. Leaves all floating, rounded, 10-34cm across.
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Duckweeds - Araceae
Common Duckweed Lemna minorNative. Found on more or less permanent bodies of water on St Mary's, St Martin's, Tresco and Bryher. Fronds 1-8 x 0.6-5mm, flattened on both surfaces and with 3 (sometimes 5) veins. Each frond develops a single rootlet.
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Least Duckweed Lemna minuta
Introduced from North America, first recorded in the UK in 1977 and on the Isles of Scilly in 1994. Frequent on St Mary's and isolated records from Tresco, Tean and St Helen's. Fronds 0.8-4 x 0.5-2.5mm, flattened on both surfaces and with just a single, obscure vein. Each frond develops a single rootlet.
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Water-ferns - Salviniaceae
Pacific Mosquito-fern Azolla filiculoides(Water-fern) Introduced from the Americas and occasionally escaping from deliberate introductions into garden ponds or from dumped garden waste. Has occurred sporadically at several wetland locations on St Mary's, St Martin's and Tresco. The fronds are green when they start to grow in spring and early summer but become strongly flushed with red later in the year, making them very obvious when they cover the surface of a pond. Note that there are six species of mosquito-fern which are all rather similar and require a microscope to tell apart. Only Pacific Mosquito-fern has officially been identified in Scilly, but other species may be present.
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