466 JUXCACEAE. VOL. I. 



Leaf-blade terete, channeled along the upper side. 



Lowest leaf of inflorescence not four lengths of the panicle ; capsule oblong to obovoid. 

 Seed tailed. 



Capsule as long as the perianth or longer. 15. /. Vaseyl. 



Capsule much shorter than the perianth. 16. /. oronensis. 

 Seed not tailed. 



Perianth i]4"-i l / 2 " long, plainly exceeded by the capsule. 17. /. Grecnei. 



Perianth iJ4"-2" long, not exceeded by the capsule. 18. /. dichotomus. 

 Lowest leaf of the inflorescence rarely less than four times as long as the panicle ; 



capsule globose-ovoid. 19. /. setaceus. 

 ** Flowers not bracteolate, in true heads on branches of the inflorescence. GRAMINIFOLII. 

 Stem erect ; capsule oblong or obovoid, obtuse at the apex. 

 Stamens 3, with red-brown anthers ; capsule not mucronate. 

 Inner perianth-parts obtuse or mucronate. 



Heads few, commonly s-io-flowered. 20. /. marginatns. 



Heads numerous, commonly 2-s-flowered. 21. /. aristulattts. 



Inner perianth parts setiform-acuminate. 22. 7. setosus. 



Stamens 6, with yellow anthers ; capsule mucronate. 23. /. longistylis. 



Stem creeping, floating, or ascending ; capsule subulate. 24. /. repens. 



2. LEAF-BLADE NOT TRANSVERSELY FLATTENED, COMMONLY TERETE, HOLLOW, PROVIDED 

 WITH SEPTA. 



* Leaf-blade usually channeled along the upper side ; septa usually imperfect, not externally evident ; 



inflorescence of 1-4 heads; plants of arctic or alpine range. ALPINI. 

 Body of the seed %" in length or more. 



Leaf-sheath not auriculate. 25. /. castaneus. 



Leaf-sheath auriculate. 26. 7. stygiiis, 



Body of the seed less than Yz" in length. 



Lowest leaf of inflorescence foliose, erect ; capsule deeply retuse at apex. 



27. /. biglumis. 

 Lowest leaf of inflorescence membranous, spreading ; capsule obtuse and mucronate at the 



apex. 28. 7. triglumis. 



** Leaf-blade not channeled along the upper side (except in 7. bitlbosus), the septa perfect (except 

 in 7. polycephalus} , and usually externally evident; inflorescence, except in depauperate 

 specimens, of several to many heads ; plants not of arctic-alpine range. SEPTATI. 



t Stamens 6, one opposite each perianth-part. 



Heads reduced to one, or rarely two flowers. 



Plant erect ; flowers several-many, paniculate. 29. 7. pelocarpus. 



Plant creeping or floating ; flowers i or 2, peduncled or sessile. 30. 7. subtilis. 



Heads 2-many-flowered. 



Epidermis not roughened. 



Plants with two kinds of leaves, one normal, the other basal, submersed, and capillary. 

 Plant low, less than 10' high. 31. 7. bulbosits. 



Plant tall, more than 10' high. 32. 7. tnilitaris. 



Plants without submersed capillary leaves. 



Capsule oblong, either abruptly acuminate or bluntly acute. 



Branches widely spreading ; capsule sharply acute, tapering into a conspicuous point. 



33. 7. articulatus. 

 Branches usually strict ; capsule broadly acute, or obtuse, with a short point. 



34. 7. alpinus. 

 Capsule subulate. 



Leaf-blades erect ; inner perianth-parts longer than the outer. 35. 7. nodosus. 

 Leaf-blades abruptly divergent from the stem ; outer perianth-parts longer than the 



inner. 36. 7. Torreyi. 



Epidermis of the leaves roughened with minute tubercles. 37. 7. cacsariensis. 



tt Stamens 3, none opposite the inner perianth-parts. 



Capsule less than three-fourths as long as the perianth. 38. 7. brachycarpus. 



Capsule more than three-fourths as long as the perianth. 

 Capsule tapering evenly into a prominent subulate beak. 



Leaf-blade vertically flattened and with incomplete septa, only rarely compressed and with 



complete se*pta. 39. 7. polycephalus. 



Leaf-blade terete or nearly so, the septa complete. 40. 7. scirpoidcs. 



Capsule obtuse to acute at the apex, sometimes mucronate, but not prolonged into a beak. 

 Seed J3"-i" long. 



Perianth about i" long, the fruiting head not more than 2" high. 41. 7. brachycephalus. 

 Perianth i l / 2 "-2" long, or if shorter, the fruiting head 2" high or more. 



Inflorescence broad ; capsule about as long as the perianth. 42. 7. canadensis. 



Inflorescence narrow ; capsule much longer than the perianth. 43. 7. brevicaudatus. 

 Seed i"-i" long. 



Perianth and mature capsule i"-z" long. 



Perianth i V^'-z" long, or if less the whole plant not 20' high. 



Perianth equaling or longer than the capsule ; heads several-many-flowered. 



44. 7. acuminatiis. 



Perianth shorter than the capsule ; heads 2-7-flowered. 45. 7. debilis. 



Perianth \"-\V\" long, the whole plant more than 20' high. 46. 7. nodattis. 

 Perianth and mature capsules 2" -3" long. 47. 7. diffusissimus. 



