Utricularia vulgaris aka Greater Bladderwort

Utricularia vulgaris belongs to the bladderwort family, Lentibulariaceae. Its common names include greater bladderwort, common bladderwort, and popweed. It grows wild in Britain and elsewhere in Europe. Its native range also covers North Africa and temperate Asia. In the wild, it lives in ponds, lakes, and ditches. It often grows in fairly deep water. These wet habitats suit its unusual way of feeding.

This rootless plant grows with vigour and forms mats. Its small leaves grow both underwater and at the surface. Bladder-like traps catch tiny prey among its leafy growth. This makes it an insect-eating plant rather than a rooted pond plant. Its foliage is deciduous. The RHS gives a garden height of 0.3–1.6 feet [0.1–0.5 metres]. Its listed spread covers the same range. Plants reach their full size in one to two years.

Yellow flowers provide its main garden display from April to August. Their shape recalls snapdragon blooms, and thin stalks hold them up. The mix of flowers and floating foliage gives it pond interest. The sources give no details about its fruit. Plants can be raised from seed or split by division. The RHS calls for no pruning, apart from removing spent flowers. It reports few problems with pests or disease.

The RHS recommends full sun and a sheltered spot. It lists acid conditions and sand that drains poorly. For growing under glass, use peat substitute with sand or perlite. Keep pots standing in a shallow layer of water. Use rainwater or pure water to keep the mix wet. The hardiness accounts differ and need care when planning outdoor use. The RHS assigns H2, which excludes freezing conditions. Plants For A Future lists USDA zones 4–8.

Plants For A Future gives low ratings for food and medicinal use. It lists leaves as edible but gives no preparation details. It also reports drinking the plant's juice for its minerals. Its claim about edible roots conflicts with the plant's rootless form. That claim should not guide use. Reported folk uses include wound poultices and use as a diuretic. These reports do not establish treatment safety or benefit. The same source lists no known hazards or weed potential. That is not proof of safety for every person or pet.