126 The Ohio Naturalist. [Vol. XIII, No. 6, 



Synopsis. 



I. Inflorescence apparently lateral. 



1. Flowers bracteolate, inserted singl}-. 



J. effusus. 

 J. balticus. 



2. Flowers not bracteolate, in heads. 



(No Ohio species.) 

 II. Inflorescence terminal. 



1. Leaf blades flat or channeled, not septate. 



a. Flowers bracteolate, never in true heads, sometimes clustered. 



J. dudleyi. 

 J. tenuis. 

 J. bufonius. 

 J. monostichus. 



b. Flowers not bracteolate, in true heads. 



J. articulatus. 

 J. marginatus. 



2. Leaf channeled or terete, hollow, with septa. 



a. Leaf blades more or less channeled, septa usually imperfect, 



not externally evident. (No Ohio species.) 



b. Leaf blade usually not channeled, septa perfect and usually 



evident externally, 

 (a), stamens 6. 



J. richardsonianus. 



J. articulatus. 



J. torreyi. 



J. nodosus. 

 (b). stamens 3. 



J. brachecephalus. 



J. acuminatus. 



J. canadensis. 



J. scirpoides. 



Key. 



\. Inflorescence apparently lateral. 2. 



1. Inflorescence terminal. 3. 



2. Perianth parts greenish, turning straw-colored, stamens 3. /. effusus. 



2. Perianth parts with a chestnut strip on each side of the midrib, 



stamens 6. J. balticus. 



3. Leaf blade flat or channeled, not septate. 4. 



-3. Leaf-blade channeled or terete, hollow, with septa. 9. 



4. Flowers bracteolate, never in true heads, sometimes clustered. 5. 

 4. Flowers not bracteolate, in true heads. 8. 



■5. Auricles at the summit of the sheathe cartilaginous and darker than 

 the stem, not extended conspicuously beyond the point of insertion. 



/. dudleyi. 

 ■5. Auricles at the summit of the sheathes scarious. 6. 



6. Inflorescence with 3-12 secund flowers along the usually dichotomously 



branched stem. J. monostichus. 

 G. Inflorescence 2-4-flowere(l, scattered along the dichotomous branches 

 or sometimes aggregate at the top but not second. 7. 



7. Bracts exceeding the inflorescence, plants perennial, flowers usually 



in clusters of 3-4. J. tenuis. 

 7. Bracts shorter than the inflorescence, plants annual, flowers scattered 

 singly along the usually dichotomous branches. /. bufonius. 



