WOOTO^T AND STANDLEY FLORA OF NEW MEXICO. 13 



Subclass 1. MONOCOTYLEDONES. 



KEY TO THE ORDERS. 



Perianth when present rudimentary or degenerate, often composed of bristles or mere 

 scales, not corolla-like, sometimes wanting. 

 Flowers in the axils of dry or chaffy, usually imbricated, bracts (scales or glumes). 



10. POALES (p. 42). 

 Flowers not in the axils of dry or chaffy bracts. 



Perianth of bristles or chaffy scales 7. PANDANALES (p. 39). 



Perianth fleshy or herbaceous, or wanting. 



Fruit baccate; endosperm present; plants 1 cm. broad or less, consisting 

 merely of a flat thallus with 1 or more roots, floating. 



11. ARALES (p. 124). 

 Fruit drupaceous; endosperm wanting; aquatics with well-developed 



stems 8. NAIADALES (p. 39). 



Perianth of 2 distinct series, the inner usually corolla-like. 



Gyno?cium of distinct carpels 1 9. ALISMALES (p. 41). 



Gynoecium of united carpels. 



Endosperm mealy 12. XYRIDALES (p. 125). 



Endosperm fleshy, horny, or cartilaginous. 



Ovary and fruit superior 13. LILIALES (p. 127). 



Ovary and fruit wholly or half inferior. 



Endosperm present; flowers regular. 14. AMARYLLIDALES (p. 145). 

 Endosperm wanting; flowers irregular. .15. ORCHIDALES (p. 148). 



Subclass 2. DICOTYLEDONES. 



KEY TO THE ORDERS. 



Corolla wanting. 

 Calyx wanting. 

 Herbs. 



Flowers monoecious or dioecious 30. EUPHORBIALES (p. 392). 



Flowers mainly perfect. 



Flowers spicate; styles wanting 16. PIPERALES (p. 154). 



Flowers axillary; styles present. 



(Callitrichaceae) 30. EUPHORBIALES (p. 392). 

 Trees or shrubs. 



Fruit many-seeded; seeds each with a tuft of hairs. 



17. SALICALES (p. 154). 



Fruit 1-seeded; seeds without tufts of hairs 42. OLEALES (p. 495). 



< !alyx present, at least in the staminate or in the perfect flowers. 



Flowers, at least the staminate, in aments or ament-like spikes; fruit a 

 nut or achene; trees or shrubs. 

 Leaves simple; ovule pendulous and anatropous.19. FAGALES (p. 163). 

 Leaves pinnate; ovule erect and orthotropous. 



13. JTJGLANDALES (p. 161). 



Flowers, at least the staminate, not in aments; fruit various; herbs, trees, or 

 sh rubs. 

 Ovary inferior. 



Flowers, at least the staminate, in involucrate heads. 



(Ambrosiaceae) 60. ASTERALES (p. 618). 



