Bogs and Acidic Peatlands of Southern New England by Marsha C. Salett
Utricularia macrorhiza L.
LENTIBULARIACEAE (Bladderwort Family)
EtymologyUtricularia is derived from utriculus, the Latin for small bottle or bag, in reference to the plants' insect-trapping bladders; macrorhiza means with large roots, or in the case of rootless Ultricularia, with large stems, from the Greek: macros = long, tall + rhiza = root, stem.
Synonyms (Common Name)Greater Bladderwort
DescriptionCommon bladderwort is the most abundant species of the aquatic bladderworts; it often forms large underwater mats. By trapping and digesting insects and other small organisms, carnivorous bladderworts -- along with pitcher plants (Sarracenia purpurea) and sundews (Drosera spp.) -- obtain nutrients, particularly nitrogen, from nutrient-impoverished bogs and fens. Aquatic or semiaquatic bladderworts catch zooplankton, tiny crustaceans, and other animals as well as insects in a mechanically unique way. Lacking roots, bladderworts float horizontally beneath the surface of the water. Their finely divided leaves bear tiny concave sacs, or utricles, that actively suck in water and prey through "trap doors" that rapidly open and shut when triggered by the touch of an organism. Inside the water-inflated bladder, digestive enzymes and bacteria dissolve the prey into nutrients that, along with the water, are absorbed into the plant. When digestion is complete -- anywhere between 15 minutes and two hours -- a partial vacuum is restored, the sac deflates, and the trap is reset.
Wetland indicator statusOBL
Plant Height2-6 inches
LeavesAlternate, finely forked leaf segments on two main stems (1-3" long) that branch at the base; small bladders borne in some leaf-forks; free-floating, horizontal.
Flower/InflorescenceYellow, 3/4" long, bilabiate (two-lipped), with spur shorter than lower lip; 6-20 flowers on stout stalks 4" -- 2' high that protrude above the water.
Flowering PeriodJuly-August
FruitSmall capsule with many seeds.
HabitatShallow waters of ponds and lakes, slow-moving streams; in water up to 4' deep.
RangeLabrador to Alaska, south to Florida and California.
(c) 1998-2006 Marsha C. Salett