Vascular Plants of North Carolina
Account for Humped Bladderwort - Utricularia gibba   L.
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Section 6 » Order Scrophulariales » Family Lentibulariaceae
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DistributionScattered over much (and probably nearly all in reality) of the Coastal Plain, and mainly in the extreme southern Piedmont and edge of the adjacent mountains (Henderson County). This is a tiny species and is easily confused with several other bladderworts, and as it has been collected from the VA border to the SC border and from the Fall Line east to the Outer Banks, it suggests that it probably does occur in every Coastal Plain county.

This is a rather Northern species of Utricularia, ranging across much of Canada and south to FL and LA.
AbundanceInfrequent, to perhaps locally fairly common, in the Coastal Plain, but rare in the southern Piedmont and adjacent southern mountains.
HabitatThis is another bladderwort found essentially in shallow, still fresh water, being found in pools, lake and pond margins, wet ditches, and other places with some shallow water.
See also Habitat Account for General Herbaceous Ponds
PhenologyBlooms from May to September, and fruits shortly after flowering.
IdentificationThis species is quite similar to several other bladderworts, in part because U. biflora is often or usually lumped into it as a variety. U. striata and U. floridana are also quite similar, though they have the shoots/leaves of two types, one with many bladders/traps and others with essentially no traps. U. gibba is best told by its tiny size, the smallest of the "mat-forming" group of yellow-flowered bladderworts, with a flowering scape only reaching about 2" tall and with a very small bright yellow flower (or two) that has a blunt spur only about 4 mm long (1/6" long). (The entire flower is barely 1/4-1/3" long and across.) The spur is stout and shorter than the lower lip, and the leaf segments (all with tiny bladders) are branched only once, as opposed to twice in U. biflora. U. biflora has a larger flower, and a longer lip that barely is longer than the relatively long and narrow spur; however, many or most taxonomists consider these points as not enough to split into full species. As might be expected, to properly identify any of these four species, you almost certainly will need to pull a few plants out of the water and examine the leaf structure, probably under a hand lens or microscope. At least, the tiny flower size should suggest U. gibba even without examining the leaves.
Taxonomic CommentsAs mentioned above, more references than not include U. biflora as a variety of U. gibba. Weakley (2018) does split them, with some hesitancy, and even states "intermediates will be encountered". U. gibba is the one that is consistently listed as a valid species.

Other Common Name(s)Floating Bladderwort, Creeping Bladderwort
State RankS4 [S4?]
Global RankG5
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