This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Aquatic herbs, with horizontal submerged leafy stems. Leaves alternate, dissected, sometimes root-like, 2-8-parted from the very base, and thus often appearing opposite or verticillate, the segments dichotomously or pinnately dissected, some or all of them bladder-bearing. Bladders with a pair of bristles and more or less other armature about the mouth. Inflorescence racemose, the raceme sometimes reduced to a single flower; scales on the lower portion of the scape, when present, basally attached, sometimes replaced by a whorl of inflated floats; pedicels from the axils of basally inserted but sometimes auriculate bracts, without bractlets. Calyx 2-lobed, the lobes concave, herbaceous, usually spreading under the mature capsule. Corolla strongly 2-lipped, the palate at the base of the lower lip, prominent, usually 2-lobed. Anthers not lobed. Capsule few-many-seeded. Seeds more or less peltate, flat-topped, the margin variously winged or wingless. [Latin, utriculus, a little bag.]
About 75 species, of world-wide distribution. Besides the following, 2 or 3 others occur in the southeastern United States. Type species: Utricularia vulgaris L.
Scape without floats.
Segments of leaves all capillary; lips of corolla nearly equal in length. Spur stout, conic, shorter than the lower lip.
1. U. gibba.
Spur slender, equalling or exceeding the lower lip.
Spur tapering from base to apex; leaves all alike, bladder-bearing; scapes 2'-5' high.
2. U. pumila.
Spur conic at base, linear above; leaves not all bladder-bearing; scapes 4-16' high.
3. U. fibrosa.
Segments of some leaves linear, flat, bristly-serrulate; upper lip of corolla about half length of lower lip.
4. U. intermedia.
Spur a mere sac; palate obsolete; pedicels recurved in fruit.
5. U. minor.
Stems free-floating, except for a single point of attachment.
Scapes 2-5-flowered, without scales; cleistogamous flowers also present.
6. U. geminiscapa.
Scapes 6-20-flowered, with 1-5 scales; cleistogamous flowers none.
7. U. macrorhiza.
Scape with a whorl of more or less united, conspicuous, inflated floats. Scape from floats to lowest pedicel 2' long or less; corolla 6 "-9" long.
8. U. radiata.
Scape from floats to lowest pedicel 3 long or more; corolla 10"-12" long.
9. U. inflata.
Utricularia gibba L. Sp. Pl. 18. 1753.
U. fornicata LeConte, Ann. Lyc. N. Y. 1: 76. 1824.
Stems creeping on the bottom in shallow water, radiating from the base of the scape; leaves alternate, mostly once or twice dichotomous, the segments few, capillary, bladder-bearing. Scapes solitary, 3/4'- 4' high, 1-3-flowered, with 1 scale or none; pedicels 1"-5" long, erect-ascending; calyx-lobes 1"-1 1/3" long; corolla yellow, the upper lip subtrian-gular, 2"-3" long, 3"-4" broad, the lower about 3" long and broad, the palate prominent, 2-lobed; spur conic, very obtuse, shorter than the lower lip; capsule globose, 11/2"-2" in diameter.
In shallow water, Maine to Michigan, south to Florida and Texas. June-Sept.