Flower:

Raceme bearing 1 to 3 bright yellow, snapdragon-like flowers at the top of a naked stem, emerging 1 to 5 inches out of the water or arising from creeping stems when land-locked. Flowers are about ¼ inch long, the lower lip and upper lip are generally the same length. At the base of the lower lip is a large inflated pouch, indented at the tip and with a spot of red in the indentation and often a few scattered red streaks along the top of the pouch. A thick, curved spur is present below lower lip that is more or less as long as the lower lip. The 2 small sepals behind the flower are green, about equal in size, round to egg-shaped with a round tip.

Leaves and stems:

Leaves are alternate, up to 3/8 inch long and fork generally 1 to 2 times. End segments of leaves can have more of a delicate, hair or thread-like (filiform) character than the section of leaf closer to the stem. Bladders occur on leaves. Stems are up to 10 inches long, either free-floating, submerged or creeping along the substrate and can create dense mats. It is not known to produce turions (overwintering, vegetative buds).

Fruit:

Fruit is a round capsule about 1/8 inch diameter, with the stub of the style persisting at the tip.

Notes:

Humped Bladderwort is quite common in north central Minnesota. For whatever reason, it was generally overlooked by earlier botanists so virtually all of the observations of it in MN have occurred since the early 1990s. It could be confused with Common Bladderwort (Utricularia vulgaris), which has rather larger flowers, ½ to ¾ inch long where U. gibba flowers are only about ¼ inch. When flowers are absent, the best way to tell them apart is to look at the leaves, as those of other Utricularia species branch and fork several times and U. gibba leaves only fork 1 or 2 times. One reference states that short-stalked, cleistogamous (self-fertile, petal-less) flowers may be produced on submerged stems, citing Taylor (1989), though this has not been verified by other references or personal observation. U. gibba has been moved around the planet in the aquatic plant trade and has become invasive in some locations where it was introduced, New Zealand in particular, and can even become weedy in aquariums and very difficult to remove. Although the commonly held view is that the bladders of bladderworts are for capturing and digesting microorganisms that provide the plant with nutrients, bladders more often have been observed to contain communities of microorganisms (bacteria, algae, and diatoms) living in the bladders, not as prey, suggesting that the bladders may also, and perhaps more importantly, serve to establish mutually beneficial relationships with some microorganisms.