Description from Flora of China
Philydrum cavaleriei H. Léveillé; Utricularia alata Benjamin; U. biflora Hayata (1911), not Lamarck (1791); U. humilis Vahl; U. recurva Loureiro; U. wallichiana Benjamin.
Annuals, terrestrial. Rhizoids and stolons capillary, branched. Traps on stolons and leaves, shortly stalked, globose, 0.5-1 mm, mouth basal; appendages 2, dorsal, subulate, curved. Leaves arising from stolon nodes, few to numerous, petiolate; leaf blade narrowly linear to linear-oblanceolate, 0.7-2(-3) cm × 1-4 mm, membranous, glabrous, vein 1, base attenuate, margin entire, apex rounded to subacute. Inflorescences erect, 2-40 cm, 1-16-flowered, glabrous; peduncle terete, 0.3-1.2 mm thick; scales few, similar to bracts; bracts basifixed, ovate, 1-2 mm, apex obtuse to acute. Pedicel spreading at anthesis but decurved in fruit, 2-5 mm, capillary, broadly winged; bracteoles subulate, much shorter than bracts, apex acute. Calyx lobes 3-4 mm at anthesis but 5-6 mm in fruit, glabrous; lower lobe ovate, slightly smaller than upper lobes, apex rounded to emarginate; upper lobe broadly ovate, apex obtuse. Corolla yellow, 6-10 mm; lower lip suborbicular, base with a prominent rounded swelling, apex rounded; spur subulate, ± as long as lower corolla lip, widely divergent, curved, apex acute; palate margin ciliate; upper lip oblong to oblong-obovate, apex rounded. Filaments ca. 1 mm, straight; anther thecae distinct. Ovary ovoid, dorsiventrally compressed; style evident; stigma lower lip semicircular, upper lip obtuse. Capsule broadly ellipsoid, 2.5-3 mm, dorsiventrally compressed, dehiscing by longitudinal dorsal and ventral slits. Seeds obliquely obovoid, 0.4-0.6 mm; seed coat with prominent elongate reticulations. Fl. Jun-Dec, fr. Jul-Jan.
Wet soil and rocks, rice fields; near sea level to 1400 m. Anhui, Chongqing, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shandong, Taiwan, Yunnan, Zhejiang [Bangladesh, Cambodia, India, Indonesia, Japan, Korea, Laos, Malaysia, Myanmar, Nepal, Papua New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; N Australia, Pacific islands (Guam, Palau)].