8 ANALYTICAL KEY 



SUBDIVISION II. ANGIOSPERMS 

 Ovules borne in a closed ovary, which at maturity becomes the fruit. 



CLASS 1. MONOCOTYLEDONS 



Stems mostly without central pith or annular layers, but having the woody 

 fibers in small separate bundles which appear, in cross section, irregularly 

 dispersed throughout the cellular tissue. Leaves mostly parallel- veined. 

 Embryo with a single cotyledon and the first leaves in germination alternate. 

 Parts of the flower usually in threes or sixes, never in fives. Our species 

 herbaceous. 



THALLOID AQUATICS WITHOUT TRUE STEMS OR LEAVES 



The plant body lens-shaped, ellipsoidal, or flask-shaped, floating 



18. LEMNACEAE, 105 



PLANTS WITH STEMS AND LEAVES 



PERIANTH FREE FROM THE OVARY OR WANTING 



Perianth wanting, or of scale-like or bristle- form divisions. 



Flowers inclosed or subtended by imbricated chaff-like scales 

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

 mostly narrow leaves, and one-seeded fruit. 



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

 tached by the middle 16. GRAMINEAE, 38 

 Stems solid, usually more or less triangular; leaf-sheaths not split; 



anthers attached at the base 17. CYPERACEAE, 84 



Flowers not inclosed in chaff-like scales (though sometimes in in- 



volucrate heads). 

 Immersed aquatics, branching and leafy, the upper leaves often 



floating 12. NAIADACEAE, 33 



Terrestrial or marsh plants. 



Flowers monoecious or dioecious. 



Flowers in cylindrical spikes 10. TYPHACEAE, 31 



Flowers in lateral heads 11. SPARGANIACEAE, 32 



Flowers perfect. 



Ovaries 3-6, separating at least when ripe 13. JUNCAGINACEAE, 36 



Ovary single, of 3 carpels 21 JUNCACEAE, 108 



Perianth always present, herbaceous or colored, never scale-like nor bristle- 

 form. 



Pistils numerous, in a head or ring 14. ALISMACEAE, 37 



Pistil 1, cells or placentae mostly 3. 

 Stamens all alike and fertile. 



Ovary of nearly separate carpels 13. JTTNCAGTNACEAE, 36 



Ovary often angled or lobed but not deeply cleft. 

 Flowers perfect ; plants not climbing. 



Divisions of the perianth alike or nearly so. 



Plant rush-like; perianth small, greenish or purplish- 

 brown 21. JUNCACEAE, 108 

 Plant not rush-like, 



