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FOC | Family List | FOC Vol. 23 | Potamogetonaceae

2. Stuckenia Börner, Bot.-Syst. Not. 258. 1912.

蓖齿眼子菜属 bi chi yan zi cai shu

Plants perennial, in fresh to saline water, totally submerged. Rhizomes present; turions absent or occasionally present; tubers absent or present. Stems elongate, terete. Stipules not tubular, adnate to base of leaf blades for 2/3 or more length of stipule, extending past adnation as free ligule. Leaves alternate, sessile, opaque, linear, channeled, turgid, veins 1-5, base acute, margin entire, apex obtuse to acute. Inflorescences spikes, submersed, capitate or cylindric; peduncles flexible, not projecting inflorescence above water surface. Pistils 4. Fruit abaxially rounded, beaked or not, turgid. Embryo with less than 1 full coil. x = 13.

Seven species: cosmopolitan; four species in China.

1 Leaf sheaths connate, tubular toward base at least when young, appearing as a closed ellipse when transversely dissected   (2)
+ Leaf sheaths convolute, appearing as a short spiral when transversely dissected   (3)
2 (1) Fruit (2.7-)2.9-3.3 mm; leaves narrowly linear, 0.7-2.4 mm wide, apex obtuse or rounded; leaf sheaths on vegetative branches 0.8-3.5 mm in diam..   1 S. amblyophylla
+ Fruit 1.9-2.6(-3) mm; leaves mostly filiform, 0.2-1.2(-1.6) mm wide, apex obtuse or bifurcate; leaf sheaths on vegetative branches 0.3-1.8 mm in diam..   2 S. filiformis
3 (1) Leaves dark green or mostly conspicuously dark brown to blackish when dried, older ones discolored, creamy whitish or grayish to bright white, hyaline edges of leaf sheaths creamy yellowish, markedly contrasting with dark sheaths; plants unbranched or moderately to richly branched near base and sparingly so above; leaf blades on main stem sheaths 80-260 mm, occasionally recurved toward apex, sometimes even twisted spirally when dried, apex obtuse to rounded.   3 S. pamirica
+ Leaves usually olive-green to dark green, sometimes brownish green to light brown, rarely brown but then leaf blade less than 80 mm and plants richly branched above, hyaline edges of leaf sheaths greenish to pale brownish, not conspicuously contrasting with sheaths; plants usually richly branched throughout or only above; leaf blades on main stem sheaths 18-120 mm, mostly ± straight, only rarely recurved toward apex when dried, apex mostly acute to acuminate, occasionally obtuse or rounded with short mucro.   4 S. pectinata

Lower Taxa


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