Bladderworts & Butterworts
What are they?
Few plants can seem more mystical and exciting than the carnivorous plants - plants that eat insects and other invertebrates! While such things may seem to be exotic and belong to the realms of tropical rainforests, we have a couple of families of carnivorous plants in East Anglia and this is one of them - the Utriculariaceae (the other being the sundews) Butterworts and bladderworts have evolved mechanisms for trapping small invertebrates and then exude special enzymes that break down the unfortunate creatures into a liquid, which is then absorbed by the plant. Bladderworts do this by having passive, sticky leaf surfaces, while bladderworts grow in water and have tiny but elaborate, bladder-like traps on their submerged leaves, that catch tiny, aquatic creatures. All are flowering plants and it is only really when they are flowering that they are at all obvious.
Where are they found?
Butterwort is a scarce plant of good-quality, wet, acidic bogs with plenty of sphagnum moss. The bladderworts are aquatic plants, typically found in clean-water dykes and wet fens, especially in the Broads, with the entire plant below the water surface, except the flower spikes (when present). All but one species are very rare in the region.
Identification
Common Bladderwort is readily told by its purple flowers and pale leaves, plus its habitat requirements (Greater Bladderwort is an introduction thqt may not still be present). The bladderworts can be difficult to tell apart, but the flowers are subtly different in shape - check the spur on the uderside of the flower. The submerged leaves and bladder placement are important, too, especially as some species can go many years without flowering.
Common Butterwort Pinguicula vulgaris
A native plant of acidic sphagnum bogs, a rare habitat in the mostly chalky groundwater habitats of East Anglia. Flowers May to July. The flowers are violet, five-petalled with a short nectar spur at the back; they are carried on long stems, well above the leaves. Leaves appear in a basal rosette and are pale, yellow-green with curled edges.
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Large-flowered Butterwort Pinguicula grandiflora
Introduced. Although native to south-west Ireland, the single record of this species from Market Weston, Suffolk probably involves a deliberate introduction. Flowers May to June. Very similar to our native Common Butterwort but with much larger, broader flowers, the flower measuring 25-35mm in length with a spur of 10-14mm.
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Greater Bladderwort Utricularia vulgaris
(Common Bladderwort) Native in species-rich fen pools and dykes, mostly in the Broads but scattered at a few sites elsewhere. Our only common species. Flowers July to August. Leaves cut to thread-like segments and carried in extensive, root-like clusters. The bladders appear scattered throughout the basal segments of the leaves. Flowers rich, deep yellow with a conical, slightly curved spur. The edges of the larger, lower petal are turned downward and conceal the spur.
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Lesser Bladderwort Utricularia minor
An extremely rare species of acidic ponds and ditches, perhaps now only in two sites in East Anglia (or less) and more common in the acidic wetlands of northern and western Britain. Flowers July to August. Leaves cut to thread-like segments and carried in small, root-like clusters. The bladders appear scattered throughout the basal segments of the leaves. Flowers pale yellow with a short, triangular spur buried underneath. The edges of the larger, lower petal are curled under.
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Intermediate Bladderwort Utricularia intermedia
A native plant of acidic pools and ditches which has not been recorded from East Anglia since the 1970s, but may still be out there. Flowers July to August. Leaves cut to finger-like segments and carried in branched clusters on long stems. The bladders appear on separate, leafless stems. Flowers bright yellow with a long, finger-like spur beneath. The edges of the larger, lower petal are broad and flare out like a skirt (see top of this page).
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