94 FLOE A OF PHILADELPHIA. 



1. JUNCUS L. Rush, Bog-eush. 



Lowest leaf of the inflorescence terete, not conspicuously channeled, erect, 

 appearing like a continuation of the stem, the inflorescence therefore 

 appearing lateral, stem leaves none. 

 Perianth-parts green, or in age straw-colored. 1. J. efusus. 

 Perianth-parts with a chestnut-brown stripe down either side of the 

 midrib. 2. J. Balticus. 



Lowest leaf of the inflorescence not appearing like a continuation of the 

 stem, or if so, conspicuously channeled along the upper side, the in- 

 florescence usually appearing terminal. 

 Leaf -blade transversely flattened (inserted with its flat surface facing 

 the stem), or terete and channeled, not provided with septa. 

 Flowers bracteolate, inserted singly on the branches of the in- 

 florescence, sometimes clustered or congested, but never in 

 true heads. 

 Annual; inflorescence, exclusive of its leaves, more than one- 

 third the height of the plant. 3. J. bufonius. 

 Perennial ; inflorescence, excluding leaves, not one-third the 

 height of the plant. 

 Leaf-blade flat, but sometimes involute in drying. 



Gauline leaves 1 or 2, rarely wanting; perianth-parts 



obtuse. 4. J. Gerardi. 



Gauline leaves none ; perianth-parts acute or acuminate. 

 Inflorescence usually much . exceeded by its low- 

 est leaf; flowers seldom plainly secund; peri- 

 anth 3.5-5.5 mm. long, usually exceeding the 

 capsule ; capsule obovoid, broadly rounded at 

 apex, the placentae intruded half way to the 

 axis. 5. J. tenuis. 



Inflorescence rarely exceeded by its lowest leaf; 

 flowers plainly secund on the branches; peri- 

 anth 2.5-4 mm. long, equalling the capsule, 

 capsule oblong, 3-sided, truncate at the apex; 

 placentae meeting at the axis. 



6. J. secundus. 

 Leaf -blade terete, channeled along the upper side. 



Lowest leaf of inflorescence not four lengths of the 

 panicle; capsule oblong to obovoid. 

 Perianth 2.5-3 mm. long, -|)lainly exceeded by 



the capsule. 7. J. Greenei. 



Perianth 3.5-4 mm. long, not exceeded by the 

 capsule. 8. J. dichotomus. 



Lowest leaf of the inflorescence rarely less than four 

 times as long as the panicle ; capsule globose-ovoid. 



9. J. setaceus. 

 Flowers not bracteolate, in true heads on branches of the inflor- 

 escence. 10. J. marginatns. 

 Leaf -blade not transversely flattened, commonly terete, hollow, provided 

 with septa. 

 Stamens 6, one opposite each perianth-part. 



Heads reduced to one, or rarely two flowers. 



11. J. pelocarpus. 

 Heads 2-many-flowered. 



Epidermis not roughened. 



Plants with two kinds of leaves, one normal, the other 

 basal, submerged, and capillary. 



12. J. militaris. 

 Plants without submerged capillary leaves. 



Capsule oblong, either abruptly acuminate or 



bluntly acute. 13. J. articulattis. 



Capsule subulate. 



