2. Stuckenia Bӧrner, Bot.-Syst. Not. 258 (1912).
Taxon Description
Perennial submerged herbs with rhizomes; turions (wintering buds) absent; stems terete. Leaves submerged, alternate, opaque, sessile, linear or filiform, channeled, margin entire, acute at base, apex acute, apiculate or obtuse; stipules not tubular, fused with leaf base forming a sheath round the stem; leaf-sheath prolonged above into free, membranous ligules. Inflorescences axillary, spikes; peduncles lax, elongated, flexible, not projecting inflorescence above water surface. Pistils 4. Stamens 4. Carpels 4. Drupelets abaxially rounded, beaked or not, turgid.
Taxon Statistics
Six species, cosmopolitan; two species in Nepal.
Key to Species
1 a. Leaf- sheaths tubular at base; leaf blades obtuse or rounded at apex ……..…………………. 1. S. filiformis
b. Leaf-sheaths open and convolute at base; leaf blades acute or mucronate at apex …… 2. S. pectinata
1. Stuckenia filiformis (Pers.) Bӧrner, Fl. Deut. Volk: 713 (1912).
Potamogeton fliformis Pers., Syn. Pl. 1: 152 (1805).
Perennial submerged herbs; rhizome slender. Stems to 40 cm, slender, mostly richly branched near base and unbranched above or sparingly branched. Leaves linear or filiform, sessile, usually less than 1 mm wide (up to 1.5 mm), 3 veined but laterals not usually visible, with large air canals on both sides of midrib. Stipules fused with leaf base, forming a sheath round the stem; leaf-sheath 1−2.2 cm, prolonged above into free, acute, membranous ligules to 2 cm. Inflorescences axillary; peduncles lax, 4−11 cm; spikes to 5 cm, flower whorls distant. Perianth suborbiculate, clawed. Stamens 4. Carpels 4. Drupelets ca. 2.5 mm, dorsal face strongly curved, ventral slightly curved, beaked.
Distribution: Nepal, E Himalaya, Tibetan Plateau, S Asia, E Asia, SW Asia, Europe, North and South America.
Altitudinal range: 2300−4800 m.
Ecology: In pond and irrigation ditch.
Flowering and fruiting time: May−July.
2. Stuckenia pectinata (L.) Bӧrner, Fl. Deut. Volk: 713 (1912).
Potamogeton pectinatus L., Sp. Pl.: 127 (1753).
Perennial submerged herbs; rhizome slender to robust. Stems to 30 cm, generally with one branch emerging from each node but sometimes two branches from one node of main stem. Leaves sessile, narrowly linear, usually less than 2 mm wide, gradually acute to apiculate, occasionally subacute to obtuse or rounded with a short mucro; leaf-sheaths open, convolute, usually white-margined. Peduncles to 1.3 cm, lax, elongated, slender. Spikes at first cylindrical, later becoming more or less interrupted, to 1.3 cm. Flowers few, minute. Carpels 4. Drupelets ovovoid−semicircular, 3−5 mm, with a short, subventral beak.
Distribution: Nepal, E Himalaya, Tibetan Plateau, Assam-Burma, S Asia, E Asia, SE Asia, Africa, Australia, Europe, North and South America, Pacific islands.
Altitudinal range: 100−3000 m.
Ecology: Occurs in shallow running water.
Flowering & fruiting time: May−December.