468 Key to the System of 



1985. Floral leaf undeveloped. 



Often very dwarf ; stems quite thin ; leaves all undeveloped ; 

 spikelet minute, solitary, terminal, rather many-flowered; 

 floral bracts blunt, without any prominent streaks ; rudi- 

 mentary sepals and petals absent ; stigmas two ; fruit pale, 

 almost orbicular. S. arenarius. 



Floral leaf developed ... 1985 



1986. Normally one stamen only. 



Seldom floating, but often emitting elongated shoots ; stems 

 thin ; leaves short, very narrow, usually only one well 

 developed for each stem, but several or few at each node ; 

 the floral leaf erect, much abbreviated, yet extending 

 beyond the inflorescence ; spikelets quite small, several or 

 few in a simple or prolifically double or triple cluster, or 

 reduced occasionally to two or one ; floral bracts blunt, 

 somewhat streaked, greenish with partly brown coloration; 

 rudimentary sepals and petals absent ; stigmas much 

 oftener three than two ; fruit smooth, mostly triangular, 

 hardly longer than broad. S. inuiidatus. 



Normally three stamens ... ... ... ... 1987 



1987. Sides of the fruit longitudinally well-streaked. 



Often very dwarf ; stems almost setular-thin ; leaves 

 capillary -narrow ; floral leaf erect, extended beyond the 

 inflorescence; spikelets one to three, minute, few-flowered; 

 rudimentary sepals and petals absent ; stigmas three ; 

 fruit very minute, roundish-turgid, slightly triangular. 



S. setaceus. 



Sides of the fruit with hardly any streaks. 



1988. Floral bracts almost streakless. 



Stems very thin ; basal leaves often undeveloped ; floral leaf 

 usually much extended beyond the inflorescence ; spikelets 

 one to three, very small, few-flowered ; floral bracts blunt; 

 rudimentary sepals and petals absent ; stigmas three ; fruit 

 bluntly triangular, smooth or slightly granular-rough. 



S. riparius. 

 Floral bract prominently streaked. 



Often very dwarf; stems quite thin; leaves very narrow; 

 the floral leaf somewhat or much extending beyond the 

 inflorescence ; spikelets quite small, few in a solitary 

 cluster, or reduced occasionally to two or one, few-flowered ; 

 floral bracts rather firm; rudimentary sepals and petals 

 absent; anthers from linear to ellipsoid; stigmas three; 

 fruit prominently triangular, slightly longer than broad. 



S. cartilagineus. 



