Montana Field Guide

Nitella, one of the genera of green algae, grows submerged in water. Nitella’s root-like rhizoids, which attach the plants to the muddy substrate, are colorless and well-developed (DiTomaso and Kyser et al. 2013). The shoot-like central axis or stipe is ridged (Swistock and Smiles 2008) with regularly-spaced nodes or joints. Between the nodes, the axis is solid. Whorls of slender, leaf-like branches develop from each node, some of these branches grow as long as 12 inches or more (DiTomaso and Kyser et al. 2013).

Nitella species are typically deep, translucent green, and very smooth and delicate (DiTomaso and Kyser et al. 2013).

Nitella can initially appear as an aquatic vascular plant because of its size; however, it lacks leaves, flowers, and seeds.

The genus Chara is similar to Nitella. However, Chara often becomes encrusted with carbonates, making it rough or gritty to the touch, and giving it an unpleasant smell like garlic or skunk when crushed. Nitella is very smooth and lacks an unpleasant odor when crushed. Chara is also grayish-green and coarse, while Nitella tends to be a deeper green and is more delicate (DiTomaso and Kyser et al. 2013; Swistock and Smiles 2008). Chara usually inhabits hard waters and Nitella prefers acidic waters with soft, muddy bottoms (Swistock and Smiles 2008).

Possessing rhizoids, a central axis, and branches, Nitella gametophytes are easily confused with some aquatic vascular plants, particularly species of Myriophyllum. However, the rhizoids are clear and do not have root caps or other structures found in roots of vascular plants. Unlike a true vascular plant stem, the Nitella axis lacks vascular tissue (xylem or phloem), and the filamentous branches of the whorls do not broaden into leaves (DiTomaso and Kyser et al. 2013).

Ponds, lakes, reservoirs, streams,d rivers, bogs, and dikes; frequently acids waters with muddy substrates (Swistock and Smiles 2008).

Nitella is an important constituent of natural aquatic ecosystems, commonly beneficial to lakes and ponds by providing food and cover to wildlife (DiTomaso and Kyser et al. 2013). Its branches provide food for waterfowl, and foraging areas for grazing insects, who eventually provide food for fish and wildlife. Like roots, the rhizoids help prevent muddy water by stabilizing the sediment (Swistock and Smiles 2008).

Excessive Nitella growth, however, may deplete water oxygen levels, jam filters, afford breeding sites for mosquitoes, impede water flow, or hamper recreational activities. Excessive growth occurs with an overabundance of nitrogen and phosphorus nutrients in the water (Swistock and Smiles 2008).

Sexual reproduction results in a zygote that develops into an oospore. The oospore stays dormant, awaiting favorable conditions for germination, undergoing meiosis and growing into the easily-visible gametophyte (DiTomaso and Kyser et al. 2013).

Vegetative reproduction occurs by fragmentation and other methods (DiTomaso and Kyser et al. 2013).

Prevention and Cultural Control

Reduce or divert nutrient-runoff away from the pond. Such runoff originates from barnyards, septic systems, crop fields, and fertilized lawns and golf courses. This can be accomplished by reducing fertilizer treatments near ponds and lakes, properly maintaining septic systems, and retaining vegetative buffers around the ponds, lakes, and streams (Swistock and Smiles 2008). Establishing native submersed plants can reduce the light and space needed by Nitella (DiTomaso and Kyser et al. 2013). To help prevent Nitella’s spread, clean and destroy stem fragments from boats, fishing gear, and other recreational equipment (DiTomaso and Kyser et al. 2013).


Physical Control

Raking, pulling, and cutting provide short-term control since spores and fragments left behind allow recolonization (Swistock and Smiles 2008; DiTomaso and Kyser et al. 2013).

Install bottom barriers in spring before plants have established much biomass and are still under 10 inches in height. Barrier materials include sheets of polyvinyl chloride, jute, burlap and other natural fibers, and small-mesh screens (DiTomaso and Kyser et al. 2013).


Biological Control

Algae-control products containing bacteria and/or enzymes are available. The bacteria and enzymes use the nutrients in the water, making them unavailable for algal growth (Swistock and Smiles 2008).