KEY. 257 



little cowl-shaped involucre (spathe). Fertile flowers : ovary 

 oblongj sessile ; style short ; stigmas 2-4. 



Najas flexilis, Kostk (903). 



819. Leaves parallel-veined, grass- or rush-like 820 



Leaves not grass- nor rush-like ; or netted-veined. 

 Flowers with a regular calyx 822 



. 830. Stem a culm. Flowers glumaceous. Leaves grass- 

 like '. 821 



Scape slender, simple, bearing a single, hairy head 

 of flowers. Calyx of 3 sepals. Sterile flowers : stamens 3 ; 

 filaments united below into a club-shaped tube around a 

 rudimentary pistil. Fertile flowers: ovary 3-cellecI, sur- 

 rounded by 3 tufts of hairs ; stigmas 3, 2-cleft. Leaves 

 lineai'-sword-shaped, tufted. 



Ijachuocaulon Michauxii, Kunth. 



821. L Grasses. Culms hollow 565 



II. Sedges. Scales 1-flowered, if not empty. 



a. Ovary surrounded by a ventricose bag, open 

 above and growing with the fruit. Stamens 3. Stigmas 2 

 or 3. Scales of the spikes 1-flowered, equally imbricated 

 around the axis. Staminate flowers separated, borne either 

 on the same spike, or ia separate sxiikes. (551) Carex (902). 



b. Ovary not enclosed in a sac. Stamens 1-3. 

 Style 3-cleft. Scales loosely imbricated, the lower ones 

 empty. Fertile spikes 1-flowered, usually intermixed with 

 clusters of few-flowered staminate spikes. Perianth not any. 

 Achenium white orwhitish. (551) Scleria. 



832. Ovaiy 3-celled ; styles or stigmas 3, often forked, 

 or style 1, 3-cleft, and stigmas 3 823 



Ovary 1 -celled ; styles (or stigmas) 1, 2 or 3, never 

 forked 825 



833. Flowers in racemes, or in a terminal spike. Ovules 

 only 1 in each cell of the ovary 824 



Flowers axillary, commonly 2 in each axil. Calyx 



5- to 6-parted. Stamens 3, their filaments united in a column 



and surrounded by 5 or 6 glands. Cells of the ovary 2- 



ovuled. Styles 3, each 2-cleft ; stigmas 6. Leaves 2-ranked. 



Fhyllauthus Caroliniensis, Walt. 



