19(18). Stems first ascending 5-20 cm. then stoloniform-creeping or floating 



and greatly elongate; capsule very narrow but obtuse 



17. J. repens. 



19. Stems erect or nearly so; capsule obovoid or tapering at the apex into a 



beak (20) 



20(19). Perianth 2-5 mm. long (21) 



20. Perianth 5-6 mm. long (22) 



21(20). Perianth 4-5 mm. long, half again as long as the capsule; anthers 

 yellow; largest transverse dimension of the compressed culm 0.5-1 

 mm 18. /. filipendulus. 



21. Perianth 2.5-3.5 mm. long, about equaling the capsule; anthers orangish to 



reddish brown; culms 1.5—3 mm. broad 19. J. marginatus. 



22(20). Sepals equaling or slightly exceeding the petals; auricles of the leaf 

 sheaths 0.5 to 1.5 mm. long; leaf blades flat; anthers cream-colored 

 or pale yellow 20. J. longistylis. 



22. Sepals shorter than the petals; auricles 1.5-3 mm. long; leaf blades channeled; 



anthers brownish 21. J: macrophyllus. 



23(18). Stamens 6 (24) 



23. Stamens 3; bract ensiform, more than half the length of the inflorescence 



22. J. ensifolius. 



24(23). Perianth segments equal in length, very narrow, often shorter than the 

 oblong, acute capsule, spreading; blades of the larger leaves 3 to 

 12 mm. wide; stems stout 23. /. xiphioides. 



24. Perianth segments unequal, the inner ones shorter, the segments broader and 



firmer in texture, usually exceeding the oblong-obovoid capsule, 

 appressed; blades of the larger leaves seldom more than 5 mm. 

 wide; stems relatively slender (25) 



25(24). Seeds tailed; styles long-exserted 24. /. Tracyi. 



25. Seeds not tailed; styles usually little if at all exserted 



25. /. saximontanus. 



26(17). Seeds caudate (27) 



26. Seeds not caudate (30) 



27(26). Stamens 3 (said to be 6 sometimes in /. trigonocarpus) (28) 



27. Stamens 6 (29) 



28(27). Stems slender, densely cespitose, 1-5 dm. tall; inflorescence strict with 

 ascending branches, with few to many heads each with 2 to 7 

 flowers; seeds (with tails) about 1 mm. long. ...26. J. brevicaiidatus. 



28. Stems simple, tough, wiry, 5-9 dm. long; inflorescence a compound panicle 



with fascicles of short branches bearing turbinate heads with 6 



to 15 flowers; seeds (with tails) 1.5-2 mm. long 



27. /. trigonocarpus. 



29(27). Stems 10-40 cm. tall, leaves mostly basal; sheaths not auriculate; inflores- 

 cence of I to 3 heads; perianth segments 4-7 mm. long; capsule 

 longer than the perianth 28. J. castaneus. 



29. Stems 5-15 cm. tall, leaves 1 to 5; sheaths auriculate; inflorescence a capitate 



cluster of 1 to 5 flowers; perianth segments 3-4 mm. long; capsule 

 about equaling the perianth 29. J. albescens. 



30(26). Stamens 6 (31) 



30. Stamens 3 (36) 



31(30). Culms 30-100 cm. tall. 2-4 mm. thick (32) 



31. Culms 5-45 cm. tall (rarely taller in J. texanus), 0.7-2 mm. thick (33) 



608 



