6. Culms compressed, 2.3 mm. thick basally, often twisted; bract 2 or 3 times 



as long as the inflorescence 4. /. mexicanus. 



7(4). Capsules obovoid, obtuse or even depressed apically; flowers numerous, 

 30 to 100 per panicle; upper sheaths bladeless 5. /. effusus. 



7. Capsule nearly spherical or slightly ovoid, apically turgid; flowers few, 2 to 



25 per panicle; upper sheaths bearing blades 6. /. coriaceus. 



8(3). Flowers in glomerules of 2 to 5 flowers, each glomerule subtended by as 

 many bracteoles as there are flowers, or an occasional flower 



also with an extra bracteole at the base of the perianth 



7. J. Roemerianus. 



8. Flowers in headlike clusters arranged in open panicles, from the axil of a 



single bractlet but without bracteoles (9) 



9(8). Perianth segments acutish to acuminate, narrowly scarious-margined, green- 

 ish or straw-colored, 4 to 6 mm. long, nearly equaling the narrowly 

 ovoid, acute or acuminate capsule 8. J. Cooperi. 



9. Perianth segments (at least the inner ones) obtuse or truncate, broadly 



scarious-margined, brown, 2 to 4 mm. long, much shorter than 

 the subglobose, obtuse mucronate capsule 9. J. acutus. 



10(1). Individual flowers with a pair of braceoles in addition to the bractlet at 

 the base of the pedicel (11) 



10. Individual flower with only one bractlet at the base of the very short pedicel 



(17) 



11(10). Annual 5-30 cm. tall; inflorescence more than half the height of the 

 plant; flowers scattered along the loosely forking branches (12) 



11. Perennials 8-125 cm. tall; inflorescence much less than half of the height 



of the plants; leaf sheaths auricled and/or prolonged (13) 



12(11). Capsule oblong, 3 to 4.5 mm. long; perianth 4 to 6 mm. long 



10. /. bufonius. 



12. Capsule subglobose to broadly ovoid; perianth 3 to 4 mm. long 



11. /. sphaerocarpus 



13(11). Capsule completely 3-celled, retuse 12. /. confusus. 



13. Capsule 1 -celled, with septa extending halfway to the center, acutish to 



obtuse, not retuse (14) 



14(13). Leaf auricles scarious or broadly scarious-margined, 1-2.5 mm. long, 



prolonged, distinctly longer than broad; plant 8-45 cm. tall 



13. J. tenuis. 



14. Leaf auricles membranous or subcoriaceus, white to brown, 0.3-1 mm. long, 



not prolonged; plants 20-125 cm. tall (15) 



15(14). Leaf blades strongly involute, appearing channeled on the ventral side; 



bractlets acute or acuminate; inflorescence diffuse 



14. /. dichotomus. 



15. Leaf blades flat or involute; bractlets obtuse or acute; inflorescence crowded 



(16) 



16(15). Perianth 4-5 mm. long; some flowers solitary, some in heads 



15. J. Dudleyi. 



16. Perianth 3.3-4.2 mm. long; flowers solitary, not in true heads 



16. /. interior. 



17(10). Leaf blades not septate or with only incomplete partitions (18) 



17. Leaf blades septate, nodulose or cross-partitioned (26) 



18(17). Blade non-septate entirely (19) 



18. Blades with incomplete septa; leaves ensiform (23) 



607 



