Small herbs (growing in water or wet places), with a 2-lipped calyx, and a 2-lipped personate corolla, 2 stamens with (confluently) one-celled anthers, and a one-celled ovary with a free central placenta, bearing several anatropous seeds, with a thick straight embryo, and no albumen.—Corolla deeply 2-lipped, the lower lip larger, 3-lobed and with a prominent palate, spurred at the base in front; the palate usually bearded. Ovary free; style very short or none; stigma 1–2-lipped. Capsule often bursting irregularly. Scapes 1–few-flowered.—The following are the two principal genera.
1. Utricularia. Calyx-lobes mostly entire. Upper lip of corolla erect. Filaments strongly incurved. Foliage dissected; bladder-bearing.
2. Pinguicula. Calyx with upper lip deeply 3- and lower 2-cleft. Corolla-lobes spreading. Filaments straighter. Terrestrial, with entire rosulate leaves next the ground.
1. UTRICULÀRIA, L. Bladderwort.
Lips of the 2-parted calyx entire, or nearly so. Corolla personate, the palate on the lower lip projecting, often closing the throat; upper lip erect. Anthers convergent.—Aquatic and immersed, with capillary dissected leaves bearing little bladders, which float the plant at the time of flowering; or rooting in the mud, and sometimes with few or no leaves or bladders. Scapes 1–few-flowered; usually flowering all summer. Bladders furnished with a valvular lid and usually with a few bristles at the orifice. (Name from utriculus, a little bladder.)
[*] Upper leaves in a whorl on the otherwise naked scape, floating by means of large bladders formed of the inflated petioles; the lower leaves dissected and capillary, bearing small bladders; rootlets few or none.
1. U. inflàta, Walt. Swimming free; bladder-like petioles oblong, pointed at the ends and branched near the apex, bearing fine thread-like divisions; flowers 3–10 (large, yellow); the appressed spur half the length of the corolla; style distinct.—In still water, Maine to Tex., near the coast.
[*][*] Scapes naked (except some small scaly bracts), from immersed branching stems, which commonly swim free, bearing capillary dissected leaves with small bladders on their lobes; roots few and not affixed, or none. (Mostly perennial, propagated from year to year by tuber-like buds.)
[+] Cleistogamous flowers along the submersed copiously bladder-bearing stems.
2. U. clandestìna, Nutt. Leaves numerous on the slender immersed stems, several times forked, capillary; scapes slender (3–5´ high); lips of the yellow corolla nearly equal in length, the lower broader and 3-lobed, somewhat longer than the approximate thick and blunt spur.—Ponds, from N. Brunswick and N. Eng. to N. J., near the coast.