Utricularia macrorhiza Leconte
Utricularia vulgaris L. p.p.
Utricularia vulgaris L. var. americana A. Gray
Utricularia vulgaris L. ssp. macrorhiza (Leconte) R.T. Clausen
Common bladderwort, bladderwort
Bladderwort is a native of the Northern Hemisphere, including most of North America and parts of temperate eastern Asia. Except for occasional racemes of yellow flowers, bladderwort remains submersed in lakes, ponds, wet marshes, and rivers and streams up to about 6' (1.8 m) deep. An underwater rootlike structure contains numerous “bladders”—small pouches that help keep the plant near the surface during flowering, then sink it during dormancy periods. But the bladders have another purpose. Common bladderwort is actually carniverous, and the bladders are spring-loaded traps that suck in water and small organisms, and digest them with enzymes and bacteria. They snap shut in about ⅟460th of a second!
Plants: Plants are not anchored and float freely, close to the surface. Rootlike structures are leaves. Underwater stems sometimes produce turions—overwintering, vegetative buds—up to about 1" (2.5 cm) around. (In many of the photos, the water surface is covered with numerous green dots. These are duckweed, not bladderwort.)
Leaves: Leaves are alternate, ¾-2" (1.9-5 cm) long, on a zig-zagged stalk with one or two main divisions from the base, these in turn forked into threadlike sections. They look more like a cloud of algae than a system of leaves. Bladders start out greenish and transparent, becoming dark red or brown to black. They are more than ¹/₁₆" (2 mm) in size.
Flowers: A stalk up to about 10" (25 cm) in height contains a raceme of 6-20 yellow flowers, each resembling snapdragons and about ½-¾" (1.3-1.9 cm) in size. They appear from late May to September.
Fruits: Round capsules less than ¼" (6.3 mm) around.
Utricularia macrorhiza at Minnesota Wildflowers
Utricularia macrorhiza on Wildflowers, Ferns & Trees of Colorado, New Mexico, Arizona, and Utah
Utricularia macrorhiza at the U.S. Forest Service Celebrating Wildflowers site
Utricularia macrorhiza on the Carnivorous Plant FAQ, courtesy of the International Carnivorous Plant Society
Utricularia macrorhiza on wisflora.herbarium.wisc.edu
Utricularia macrorhiza on the Connecticut Botanical Society's Connecticut wildflowers site
Utricularia macrorhiza on SEINet—the Southwest Environmental Information Network
Utricularia macrorhiza from the Jepson Manual
Utricularia macrorhiza description by Thomas H. Kent, last updated 16 Jul 2020.