Description from Flora of China
Utricularia caerulea Linnaeus var. graminifolia (Vahl) P. K. Bhattacharyya; U. conferta Wight; U. equiseticaulis Blatter & McCann; U. parviflora Buchanan-Hamilton ex Smith; U. pedicellata Wight; U. purpurascens Graham; U. subrecta Lace; U. uliginoides Wight.
Perennials or perhaps sometimes annuals, terrestrial. Rhizoids and stolons capillary, branched. Traps on rhizoids, stolons, and leaves, stalked, globose, 0.5-1.3 mm, mouth basal; appendages 2, dorsal, simple, subulate. Leaves numerous, from stolon nodes, glabrous; leaf blade linear to narrowly obovate, 0.4-2 cm × 0.8-3 mm, membranous, veins 3, base attenuate onto petiole, margin entire, apex rounded to subacute. Inflorescences erect, 2.5-30 cm, 1-6-flowered, glabrous; peduncle terete, 0.4-1 mm thick; scales few to many, similar to bracts; bracts basifixed, ovate, 2-2.5 mm, apex acuminate. Pedicel ascending, 3-13 mm, filiform, narrowly winged; bracteoles basifixed, subulate, slightly shorter than bracts. Calyx lobes ovate, 3.5-6 mm; lower lobe slightly smaller than upper lobe, apex shortly 2-dentate; upper lobe apex acute to acuminate. Corolla mauve to violet, 0.7-1.3 cm; lower lip suborbicular, base with a conspicuous swelling, apex rounded; spur subulate, ± as long as lower corolla lip and widely diverging from it, straight or slightly curved; palate with a raised ciliate margin; upper lip oblong, apex rounded. Filaments ca. 1.5 mm, straight; anther thecae distinct. Ovary ovoid; style evident; stigma lower and upper lips semicircular. Capsule ellipsoid, 2-3 mm, slightly dorsiventrally compressed, dehiscing by a longitudinal ventral slit. Seed ovoid to ellipsoid, 0.3-0.4 mm; seed coat with prominent elongate reticulations. Fl. May-Dec, fr. Jun-Jan.
Marshes, swamps, streamsides, wet soil among rocks; 100-2100 m. S Fujian, Guangdong, Yunnan [India, Myanmar, Sri Lanka, Thailand].