Chippewa Flowage Area Property Owners Association

Starry stonewort: Nitellopsis obtusa

Starry stonewort is not here yet. Let’s keep it that way!

Nitellopsis obtusa (Desvaux in Loiseleur) J. Groves, (1919)

Common name: starry stonewort

Synonyms and Other Names: Chara obtusa, C. ulvoides, C. stelligera, Lychnothamnus stelliger, Nitella stelligera, N. stelligera var. ulvoides, N. ulvoides, N. bertolonii, Nitellopsis aculeolata, N. obtusa var. ulvoides, N. obtusa f. ulvoides , Nitellopsis stelligera, Tolypellopsis obtusa, T. stelligera, T. ulvoides

Identification:

Stem/Rhizoids: Nitellopsis obtusa has long, variable-length, relatively straight branches arranged in whorls that attach at acute angles to stem nodes. Internodal cells of N. obtusa are quite large, often on the order of a few centimeters long (Steudle and Zimmermann 1977, Yoshioka and Takenaka 1979). Most stem and branch cells are around 1 mm in diameter, while stems can reach up to 80 cm long (Hargeby 1990, Sher-Kaul et al. 1995). Heights of 2 m have been observed at a depth of 9 m in one Michigan lake (Pullman and Crawford 2010), although rate of growth is uncertain. N. obtusa is light green when actively growing. Creamy white bulbils may occur at the base of the main axis just below the substrate-water interface and on branches of the main axis at nodes; rhizoids are star-shaped.

Reproductive structures: Plants are dioecious. Female oogonia, with bracts on either side, form at the upper nodes of branchlets. Plants can form gyrogonites, which are calcified, spiral-shaped fructifications (Bharathan 1983, 1987, Schloesser et al. 1986, Soulie-Marsche et al. 2002). Orange to red oocytes can occur at the nodes of branches (Pullman and Crawford 2010).

Look-a-likes: Chara spp. musk-grass; Nitella spp. brittlewort; other Nitellopsis spp. stonewort. Key differences are the star-shaped rhizoid, the orange-colored oocyte, irregular branching, and lack of a garlic odor (Pullman and Crawford 2010).
Size: Up to 2 m in height (Pullman and Crawford 2010); main stem up to 80 cm long (Hargeby 1990).

Native Range: Nitellopsis obtusa is native to Eurasia, from the west coast of Europe to Japan (Mills et al. 1993, Soulie-Marsche et al. 2002).

Source USDA