32(31). Inflorescence of spherical many-flowered heads in a cluster subtended 



by a long pointed bract; capsule subulate, 4—5 mm. long 



30. J. Torreyi,. 



32. Inflorescence of hemispheric or top-shaped heads on spreading branches; 



capsule 3-angled, ovate, tapering to a conspicuous tip, 3 mm. long 

 31. /. articulatus. 



33(31 ). Capsule trigonous and oval or obovoid (34) 



33. Capsule subulate-pointed (35) 



34(33). Heads usually solitary, densely many-flowered; perianth dark brown, 



3.5-4 mm. long; capsule narrowly oval, emarginate 



32. /. Mertensianus. 



34. Heads 4 to 12, 5- to 10-flowered; perianth brown, 2-3 mm. long 



33. /. badius. 



35(33). Inflorescence 2-5 cm. long; capsule slightly exserted, 3 to 4 times as 

 long as broad; anthers a little shorter than their filaments; plants 

 of w. Texas and New Mexico 34. /. nodosus. 



35. Inflorescence at maturity mostly 5-10 cm. long; capsule at maturity subulate- 



beaked, more than 4 times as long as broad, much-exserted; anthers 

 much longer than their filaments; endemic to n.-cen. Tex. and the 

 Edwards Plateau 35. J. texanus. 



36(30). Heads nearly spherical when mature, 15- to 100-flowered (37) 



36. Heads or glomerules hemispherical or narrower at maturity, 2- to 10-flowered 



(42) 



37(36). Capsules 1.5-2.2 mm. long 36. J. brachycarpus, 



37. Capsules longer (38) 



38(37). Capsules narrowly ovoid to elliptic-ovoid, 2.5-3.3 mm. long, about 

 equaling the petals but usually shorter than the sepals, apically 

 blunt and sometimes apiculate; sepals and petals paleaceus, drying 

 semirigid 37. J. acuminatus f. sphaerocephahis. 



38. Capsules usually subulate (at least terminally), usually at least 3.5 mm. long, 



apically acute; sepals and petals semirigid and subspinescent (39) 



39(38). Uppermost sheath (not that of the bract of the inflorescence) much 

 longer than its blade 38. /. megacephalus, 



39. Uppermost sheath shorter than its blade (40) 



40(39). Flowering culms 1-1.5 mm. thick near the middle, arising erect and 

 separately from short whitish rhizomes; leaves few, scattered on 

 the culm, the blades essentially terete and about 1 mm. thick near 

 the middle; sepals 0.5-0.8 mm. broad; petals 0.3-0.5 mm. broad 

 39. /. scirpoides. 



40. Flowering culms 2-4 mm. thick near the middle, a few ascending in a tuft 



from a non- or sub-rhizomatous base; leaves several in a basal 

 cluster and also scattered on the culm, the blades laterally flattened 

 and 3-7 mm. thick in the larger (dorsiventral) dimension; sepals 

 0.7-1.4 mm. broad; petals 0.5-1 mm. broad (41) 



41(40). Blades 4-7 mm. thick in the larger dimension, with many weak incom- 

 plete septa; leaves and stems greenish, mostly crushed flat in pre- 

 pared specimens; culms 6-10 mm. thick basally 



40. J. polycephalus. 



41. Blades 3-6 mm. thick in the larger dimension, with several tough complete 



septa; herbage grayish or olivaceous, mostly tough and resistant 

 to crushing; culms 3-5 mm. thick basally 41. J. validus. 



42(36). Capsules at least half again as long as the petals, 4-5.2 mm. long 



42. /, diffusissimus. 



609 



