Annual herb
Stem: free-floating or creeping along soil in shallow water. Bladders form on specialized branches.
Leaves: many, 0.5 - 2 cm long, often three-parted at base and forking one to three times into flat and slender segments with toothed margins (10x magnification required). The segments do not become much thinner with further dissection, and the end segments are blunt-tipped.
Flowers: borne two to four on a stalk (scape), yellow petals are two-lipped with lower lip twice as long as the 8 - 12 mm upper lip and having a projection in the center. The spur (extended sac at base of petals) is cylindrical and almost as long as the lower lip.
Fruit: a two-valved capsule containing small seeds.
Similar species: Utricularia radiata, Utricularia minor, Utricularia macrorhiza, Utricularia geminiscapa, and Utricularia gibba are other aquatic or amphibious Utricularia species with dissected leaves. The flower stalk of Utricularia radiata has a whorl of leaves with inflated petioles. Utricularia macrorhiza, U. geminiscapa, and U. gibba have leaf divisions that are circular in cross-section. Utricularia minor has terminal leaf divisions that are non-toothed and traps that are borne on the leaves.
Flowering: late May to early September
Habitat and ecology: Rare in shallow water of marl flats, alkaline bogs, and fens.
Occurence in the Chicago region: native
Etymology: Utricularia comes from the Latin word utriculus, meaning "a small bottle."This refers to the insect-trapping bladders on the leaves and runners of the bladderworts. Intermedia means intermediate.
Author: The Morton Arboretum
