Submersed Plants

Species: Utricularia inflata Walt., swollen bladderwort
Utricularia vulgaris L., common bladderwort or greater bladderwort
Family: Lentibulariaceae

Bladderworts are carnivorous plants with delicate, finely-divided underwater leaves and emergent snapdragon-like yellow flowers. The most distinctive underwater features are the small bladder-like traps. These traps use a vacuum to capture small invertebrates or even tiny fish that trigger the trap door. Enzymes are secreted to digest the prey which provides the plant with nutrients. Several bladderwort species are found in Washington.

Submersed Plants Icon
Leaf: No true leaves. Instead both species have green, highly branched, finely divided underwater leaf-like stems with small seed-like bladders. Bladderwort plants often appear dense and bushy underwater. Swollen bladderwort has a distinctive spoke-like whorl of 4 to 10 wedge-shaped floating leaves, 4 to 9 cm long, which supports the flower stalk. 

Stem: The branched stem is up to 2 m long and can be floating, submersed, or partly creeping on the sediment, sometimes anchored at the base by root-like structures. 

Flower: Yellow, snapdragon-like flowers occur above the water. Swollen bladderwort: flowers to 20 mm wide, in groups of 3 to 14 on upright stalks supported by a spoke-like float. Flowers in spring in Washington. Common bladderwort: flowers to 25 mm wide on stout stalks, with a prominent spur projecting below the lower lip of the flower. Flowers often have faint purple-brown stripes. Flowers in late summer.

Fruit: Capsule contains many seeds. Swollen bladderwort: fruit stalk (pedicel) to 35 mm long. Common bladderwort: fruit stalk (pedicel) to 20 mm long. 

Root: None.

Propagation: Fragments, seeds. Swollen bladderwort: may form tiny tubers, small coiled winterbuds. Common bladderwort: may form very large (4-5 cm across) bright green winterbuds.  

Importance of plant: Food and cover for fish. Food for muskrats and waterfowl. Habitat for aquatic invertebrates. Swollen bladderwort: can become invasive.

Distribution: Swollen bladderwort: principally in eastern North America, but introduced and increasingly present west of the Cascades. Common bladderwort: throughout the northern hemisphere.

Habitat: Floating freely in shallow water, or loosely attached to the sediment.

May be confused with: White water buttercup (Ranunculus aquatilis) and watermilfoils (Myriophyllum spp.) when without bladders or flowers. Invasive, Non Native Plant Icon Other less common bladderworts (Utricularia intermedia and U. minor) are much smaller with flowers less than 9 mm wide. U. intermedia has bladders on separate stems from the "leaves".

Nonnative icon for U. inflata only

Photographs: Flowering Utricularia inflata plants, U. vulgaris plant, closeup of U. vulgaris bladders.  

Line Drawings: Utricularia vulgaris, Utricularia inflata

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