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DescriptionThe leaves are bright green, <1 mm wide, 20 -115 mm long, elliptical in cross section with pointed, slightly toothed tips. The leaves are held in membranous sheaths, 5 -22 mm in length at their base. A system of fine, slender rhizomes and fine roots holds the plants into the substratum. Flowers and fruits are borne on a characteristic coiled stalk (the peduncle), which may hold the flowers at the water surface or underwater. However, growth form is very variable, including long, tall plants in deep water, or tightly branched short plants in shallow, clear water. Dwarf forms have also been observed.The taxonomy of Ruppia spp. is difficult and under revision. Ruppia maritima may be confused with Ruppia cirrhosa (syn. spiralis), which has dark green, wider (0.4 -1.4 mm) elongate leaves, with blunt tips, and whose flowers have a relatively longer peduncle (Preston, 1995). Dwarf forms of Ruppia maritima may be confused with the needle spike-rush Eleocharis acicularis.