ANALYTICAL KEY 11 



M. Perianth free from the ovary or none N. 



N. Perianth wanting or of scale-like or bristle-form divisions O. 



O. Flowers inclosed or subtended by imbricated husk-like 



scales (glumes) ; grass-like plants with jointed stems, 



sheathing (mostly narrow) leaves, and 1-seeded fruit. 



Stems hollow, round or flattened; leaf-sheaths split; 



anthers attached by the middle GRAMnsrBAE, 86 



Stems usually more or less triangular, solid ; leaf-sheaths 



not split ; anthers attached at the base Cyperaceae, 171 



O. Flowers not inclosed in husk-like scales (though sometimes in 

 involucrate heads) P. 

 P. Immersed aquatics, branching and leafy, the upper leaves 

 often floating. 

 Flowers perfect Najadaceae, 69 



Flowers monoecious or dioecious. 

 Flowers in globose heads Spabganiaceab, 68 



Flowers axillary, solitary Najadaceae, 69 



P. Terrestrial or marsh plants Q. 

 Q. Leaves petioled, the blade net-veined Abaceae, 257 



Q. Leaves linear or sword-shaped, parallel-veined, not petioled R. 

 R. Flowers monoecious or dioecious. 



Flowers in cylindrical spikes Ttphaceae, 67 



Flowers in heads. 

 Heads spheroidal, pubescent, involucrate Eeiocaulaceae, 260 

 Heads globose, glabrous, not involucrate Sparganiaceae, 68 

 R. Flowers perfect. 



Flowers in a dense spike, this borne on the margin 



of a 2-edged scape ; root aromatic Acorus, 258 



Scapes or peduncles cylindrical. 



Ovaries 3-6, separating at least when ripe Juncaqinaceae, 79 

 Ovary single, 3-carpeled Juncaceae, 267 



N. Perianth always present, herbaceous or colored, neither scale-, 

 like nor bristle-form S. 

 S. Pistils numerous in a head or ring Alismaceae, 80 



S. Pistil one, compound (cells or placentae mostly 3) T. 

 T. Stamens 3. 



Moss-like, aquatic ; flowers solitary Matacaceae, 263 



Rush-like marsh or bog plants ; flowers in spikes, racemes, 

 or heads. 

 Flowers racemose or spicate Juncaginaceae, 79 



Flowers in dense scaly heads Xybidaceae, 262 



T. Stamens i Maianthemum, 291 



T. Stamens 6 U. 

 U. Stamens all alike and fertile. 



Gray scurfy moss-like epiphyte Bbombliaceae, 265 



Not epiphytic. 

 Ovary of nearly separate carpels Juncaginaceae, 79 



Ovary (often angled or lobed) not deeply cleft. 

 Divisions of the perianth alike or nearly so. 

 Perianth woolly Haemodokaceae, 296 



Perianth not woolly. 

 Plant rush-like; perianth small, greenish or 



purplish brown Juncaceae, 267 



