[+][+] No cleistogamous flowers.
[++] Pedicels recurved in fruit; corolla yellow.
3. U. vulgàris, L. (Greater Bladderwort.) Immersed stems (1–3° long) crowded with 2–3-pinnately many-parted capillary leaves, bearing many bladders; scapes 5–12-flowered (6–12´ long); corolla closed (6–9´´ broad), the sides reflexed; spur conical, rather shorter than the lower lip, thick and blunt in the European and the high northern plant; in the common American plant less thick and rather acute.—Common in ponds and slow streams, Newf. to Minn., south to Va. and Tex., and westward. (Eu., Asia.)
4. U. mìnor, L. (Smaller B.) Leaves scattered on the thread-like immersed stems, 2–4 times forked, short; scapes weak, 2–8-flowered (3–7´ high); upper lip of the gaping corolla not longer than the depressed palate; spur very short and blunt, or almost none.—Shallow water, E. Mass, to Minn., south to N. J. and Ark., and westward. (Eu.)
[++][++] Pedicels erect in fruit, few and slender; corolla yellow.
5. U. gíbba, L. Scape (1–3´ high) 1–2-flowered, at base furnished with very slender short branches, bearing sparingly dissected capillary root-like leaves and scattered bladders; corolla 3–4´´ broad, the lips broad and rounded, nearly equal; the lower with the sides reflexed, exceeding and approximate to the very thick and blunt conical gibbous spur.—Shallow water, Mass. to Mich., south to Va. and Ill.; Mt. Desert (F. M. Day).
6. U. biflòra, Lam. Scape (2–5´ high) 1–3-flowered, at the base bearing somewhat elongated submersed branches with capillary root-like leaves and numerous bladders; corolla 4–6´´ broad, the spur oblong, equalling the lower lip; seeds scale-shaped.—Ponds and shallow waters, S. Ill. and Iowa to Tex.; also S. Va. (?), and Barnstable, Mass. (W. Deane).
7. U. fibròsa, Walt. Leaves crowded or whorled on the small immersed stems, several times forked, capillary; the bladders borne mainly along the stems; flowers 2–6 (6´´ broad); lips nearly equal, broad and expanded, the upper undulate, concave, plaited-striate in the middle; spur nearly linear, obtuse, approaching and almost equalling the lower lip. (U. striata, LeConte.)—Shallow pools in pine barrens, L. Island and N. J. to Fla. and Ala.
8. U. intermèdia, Hayne. Leaves crowded on the immersed stems, 2-ranked, 4–5 times forked, rigid, the divisions linear-awl-shaped, minutely bristle-toothed along the margins; the bladders borne on separate leafless branches; upper lip of corolla much longer than the palate; spur conical-subulate, acute, appressed to the very broad (6–8´´) lower lip and nearly as long as it.—Shallow pools, Newf. to N. J., west to Iowa, Minn., and northward. (Eu., Asia.)
[++][++][++] Pedicels erect in fruit, rather long; corolla violet-purple.