Common Bladderwort

Over the next few weeks as you travel our region you may notice lots of yellow flowers sticking up from the surface of cattail sloughs, stock dams, and other quiet and shallow bodies of water. That is most likely common bladderwort. Most casual observers will be quite surprised to learn that these plants are carnivorous.

Most of the bladderwort we see in our region is the common bladderwort, or Utricularia vulgaris. In North Dakota it is particularly common north and east of the Missouri River, but may be found southwest of the river as well.

Bladderwort grows while free floating in a body of water. The only part of the plant above water is the flower stock and flower. The bright yellow flowers are irregular, having an upper and lower lip, similar to that of a snapdragon. The plant has no roots, and the leaves of bladderwort, like some other submersed aquatic plants are very finely divided and thread-like.

But it is the numerous bladders that are the conversation pieces of these plants.

Each plant usually contains many small oval or pear shaped bladders that are around 1/8 of an inch across, and serve to trap and digest protistans and small invertebrates such as copepods, and fairy shrimp.

Each bladder is hollow with a small trap door or valve. I have read that there is sugary mucus around the trap door which may serve in attracting prey, sealing the trap door, or both. At any rate, the inside of the bladder is under negative pressure or a vacuum.

Sticking out of the bladder near the trap door are tiny trigger hairs. If an animal bumps into these trigger hairs, the trap door opens, suck in water and the soon to be unlucky prey, and slams back shut. The entire operation occurs within a staggering time of around a 10,000th of a second. The bladderwort then digests its meal with the help of special enzymes, expels the water, and resets the trap.

Chuck Lura

Natural North Dakota is supported by NDSU Central Grasslands Research Extension Center and Minot State University-Bottineau, and by the members of Prairie Public. Thanks to Sunny 101.9 in Bottineau for their recording services.