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      Utricularia is the largest genus of what has long been thought to be carnivorous plants, with more than 220 species in the world. Utricularia trap small organisms in their tiny bladders (their utricula) which have a trap door that is triggered by hairs on the door. When prey comes in contact with the hairs the door opens in a millisecond, sucking the animal in, and closing in about 2.5 milliseconds.

     The International Carnivorous Society web page adds this information:

The bladder releases digestive enzymes and digests the [trapped] creature. Depending upon the size of the prey, it takes a few hours to a few days to consume the prey. Very large prey, such as worms, that are not completely trapped may be digested over long periods of time as the bladder digests the prey-parts in the trap, and as it slowly draws the rest of the prey into the trap as it dissolves, all while still alive.

    Analysis of Utricularia bladders has revealed that plant material (mostly single celled algae) is also trapped in the bladders. The research concluded,

Utricularia benefits both from high nutrient concentrations in the water and from successful prey capture. Abundant traps are formed only by well-nourished plants growing in waters rather rich in nutrients. In such water bodies, prey objects of all kinds are more abundant as well. Thus, the benefit gained from prey is much higher in mesotrophic [having a moderate amount of dissolved nutrients] than in oligotrophic [having a deficiency of plant nutrients] waters. The contribution of pollen grains and algae to the nutrition of the plant is comparable with the benefit gained from prey animals.

   Utricularia are not strictly carnivorous.

   Two Utricularia are shown on below.

    Utricularia macrorhiza has leaves 20-50 mm long, 2-3 times pinnately branched with a main rachis, the leaf segments are terete (round in cross section); bladders are on the leaves; racemes are 8-20 flowered and corollas are bright yellow, 12-18 millimeters long with a 5-7 mm long spur.

    Utricularia minor has leaves 2-15 mm long, palmately 3-divided from the base, the 3 divisions 1-3 branched, the leaf segments are flat; bladders are not always on the leaves; racemes are 1-9 flowered and corollas are dingy yellow, 5-8 millimeters long with a 2.5-3 mm long spur (some sources indicate that a well-defined spur is absent or just a nub).

    Most morphological details are from Intermountain Flora.
    See Wikipedia for an over-view of Utricularia.
Utricularia macrorhiza
Utricularia macrorhiza.  Synonym:  Utricularia vulgaris. (Greater Bladderwort)
Lentibulariaceae (Bladderwort Family)

Montane, subalpine. Ponds. Summer.
Haviland Lake Trail, July 1, 2005.

Often just the tiny yellow flower of Utricularia macrorhiza shows above the water surface.  In this picture you can see the flower stem system supporting five fully opened flowers and a number of buds.  Submerged are the leaves and bladders.  (See below.)

Linnaeus named and described this genus and species in 1753.  "Utricularia" is Latin for "a little bag" and refers to the bladder pods (shown below). The Flora of the Four Corners Region points out that macrorhiza (meaning "large roots") is a misnomer since Utricularia lack roots.  
Utricularia macrorhiza
Utricularia macrorhiza.  Synonym:  Utricularia vulgaris. (Greater Bladderwort)
Lentibulariaceae (Bladderwort Family)

Montane, subalpine. Ponds. Summer.
Haviland Lake Trail, July 1, 2005.

Flowers are about 12-18 millimeters long

with a 5-7 millimeter spur.Utricularia macrorhiza

 
Utricularia macrorhiza
Utricularia macrorhiza.  Synonym:  Utricularia vulgaris. (Greater Bladderwort)
Lentibulariaceae (Bladderwort Family)

Montane, subalpine. Ponds. Summer.
Haviland Lake Trail, July 1, 2005.

The web of submerged growth appears to be roots but it is actually finely divided leaves. Utricularia has no roots.  In the photograph at left the plant is coated with pond growth, but the bladders clearly show, and above the center of the photograph where I cleaned off the pond growth, you can see the pinnately branched, vein-like leaf system.


Arrows point to some of the leaf segments.Utricularia macrorhiza

 

 

Utricularia minor
Utricularia minor (Lesser Bladderwort)
Lentibulariaceae (Bladderwort Family)

Montane, subalpine. Ponds. Summer.
Grindstone Lake Trail, August 25, 2006.

Utricularia minor grows in shallow ponds and slow moving streams.  It is a very slender plant but it spreads in easily observed masses.  Leaves are minute and are cut into fine divisions.  Yellow flowers (not shown) are about half the size of those of U. macrorhiza. 

Marian Rohman found the Grindstone population of U. minor, the first known specimens from the West Slope of Colorado. 

U. minor is considered a Colorado imperiled species. Click to read "Utricularia minor L. (lesser bladderwort) A Technical Conservation Assessment". See page 18 for a detailed description of U. minor.

Utricularia minor is circumboreal and in the northern hemisphere it is found across Canada and in all western United States (where it is rare to uncommon) and across the northern tier of states where it is more common. U. minor is not found in New Mexico or in the Four Corners area of Utah but is in Apache County, Arizona.

Linnaeus named this species in 1753 from specimens collected in Europe.
Utricularia minor
Utricularia minor (Lesser Bladderwort)
Lentibulariaceae (Bladderwort Family)

Montane, subalpine. Ponds. Summer.
Grindstone Lake Trail, August 25, 2006.

Air bubbles encase the floating stems.

Leaves are palmately divided in 2 or more often 3 divisions and these divisions are again divided 2 or 3 times.
Utricularia minor
Utricularia minor (Lesser Bladderwort)
Lentibulariaceae (Bladderwort Family)

Montane, subalpine. Ponds. Summer.
Grindstone Lake Trail, August 25, 2006.

Bladders are not always attached to the leaves of Utricularia minor. Arrows in the photograph at left point to the bladders attached to the stems, either submerged (the two brown bladders on the right) or floating on the surface (the two bladders on the left).

 

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Utricularia macrorhiza

Range map for Utricularia minor