The Original Mystery Plant

Photo by John Nelson

There are certain streams in the sandhills here in the midlands of South Carolina which are often referred to as "blackwater" streams for their water is typically dark-colored but clear, something like tea. This coloration comes from dissolved organic compounds leached from rotting vegetation in the surrounding bottomlands.

The water of these streams carries very little silt and is generally acidic (low pH). Additionally, the water often flows with considerable velocity depending upon the width and depth of the stream and is relatively high in dissolved oxygen. These streams and the wetland forests associated with them are strikingly beautiful and filled with a great variety of plant and animal species. The best way to study one of these streams is from the safe confines of a kayak or canoe. The streams are commonly sandy-bottomed, but the margins are often quite boggy.

This week's mystery plant is an alga (pronounced AL-ga) which is the singular term for a species within the huge group of organisms called algae. Most people tend to dismiss the algae as unimportant or perhaps annoying and indeed, some species can develop troublesome growths at times. Most modern biologists consider the algae not to be plants at all but maintained within a separate category. Whether true plants or not, these organisms are fascinating, and they occupy many ecologic niches around the world.

Photo by Clint Cook

This blackwater mystery is a magically slippery thing, composed of thousands of tiny, stringy branches covered with mucilage. It's fairly common in the eastern U.S. and in the Southeast on the coastal plain. It attaches itself and grows from submerged logs or sticks dramatically swaying with the current down below. Holding a bunch of it is a very unusual experience. It feels like cold, delicate spaghetti coated with water-soluble olive oil. In fact, this species is classified as one of the red algae (rhodophyta), a large group of mostly marine species. The one pictured here is one of the few freshwater reds there are and in fact, is more greenish or bluish than red. Sometimes it's even black when viewed from above.

You may already know some of the red algae, especially if you are fond of Japanese cuisine. Nori is a red alga used for wrapping sushi.

Answer to last week's mystery plant

Pawpaw, Asimina triloba

Dr. John Nelson is the curator of the USC Herbarium.

To learn more about the Herbarium, call him at

777-8196. His department also offers free plant identification.

www.herbarium.org