246 FLORA. 



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

 PROVIDED WITH SEPTA. 



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

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

 Body of the seed i mm. in length or more. 



Leaf-sheath not auriculate. 20. J. castaneus. 



Leaf-sheath auriculate. 21. J. stygius. 



Body of the seed less than i mm. in length. 



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



22. J. biglumis. 

 Lowest leaf of inflorescence membranous, spreading ; capsule obtuse and mucro- 



nate at the apex. 23. J. triglumis. 



** Leaf-blade not channeled along the upper side (except in^. bulbosus), the septa per- 

 fect (except in_/. polycephalus), and usually externally evident; inflorescence, ex- 

 cept 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. 24. J. pelocarpus, 



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 2.5 dm. high. 25. J. bulbosus. 



Plant tall, more than 2.5 dm. high. 26. J. militaris. 



Plants without submerged capillary leaves. 



Capsule oblong, either abruptly acuminate or bluntly acute. 



Branches widely spreading ; capsule sharply acute, tapering into a con- 

 spicuous tip. 27. /. articulatus. 

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



tip. 28. J. Richardsonianus. 



Capsule subulate. 



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



29. J. nodosus. 

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



longer than the inner. 30. J. Torreyi. 



Epidermis of the leaves roughened with minute tubercles. 31. J. Caesariensis. 



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



Capsule less than three-fourths as long as the perianth. 32. J. 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 septa. 33. J. polycephalus. 



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



Uppermost cauline leaf with a well-developed blade. 



34. J. scirpoides. 

 Uppermost cauline leaf with a rudimentary blade rarely exceeding 3 dm. in 



length. 35. J. megacephalns. 



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

 a beak. 



Seed 0.6-2 mm. long. 



Perianth about 2 mm. long, the fruiting head not more than 4 mm. high. 



36. J. brachycephalus. 

 Perianth 3-4 mm. long, or if shorter, the fruiting head 4 mm. high or more. 



37. /. Canadensis. 

 Seed 0.4-0.5 mm. long. 



Perianth and mature capsule 2-4 mm. long. 



Perianth 2.5-4 mm ' long, or if less the whole plant not 5 dm. high. 



38. J. acumitanus. 

 Perianth 2-2.5 mm - lon g, the whole plant more than 5 drr. high. 



39. J. robustus. 

 Perianth and mature capsules 4-6 mm. long. 40. J. diffusissimus. 



I. Juncus effusus L,. COMMON RUSH. BOG RUSH. SOFT RUSH. (I. F. f. 

 919.) Plant 0.41.2 m. high, tufted, erect. Rootstock branching, proliferous; 

 stem soft, merely striate beneath the inflorescence; basal leaf-blades reduced to 

 filiform rudiments; inflorescence many-flowered. 2-10 cm. high, in one form con- 

 gested; lowest bract of the inflorescence, 5-25 cm. long; perianth 2-3 mm. long, its 

 parts green, lanceolate, acuminate; anthers shorter than the filaments; capsule obo- 

 void, 3-celled, muticous, regularly dehiscent; seed 0.4-0.5 mm. in length, reticulate 



