xviii KEY TO THE ORDERS. 



2. Angiospermae. 



Cotyledon i: stem endogenous. Subclass i. MONOCOTYLEDONES. n 



Cotyledons normally 2: stem exogenous (with rare exceptions). 



Subclass 2. DlCOTYLEDONES. 9 1 



i. MONOCOTYLEDONES. 



Perianth rudimentary or degenerate, its members often bristles or mere 



scales, not corolla-like, or wanting. 

 Flowers not in the axils of dry or chaffy bracts (scales or glumes). 



Perianth of bristles or chaffy scales. Order 9. PANDANALES. n 



Perianth fleshy or herbaceous, or wanting. 



Fruit baccate; endosperm present. . Order 14. ARALES. 74 



Fruit drupaceous; endosperm wanting. Order 10. NAIADALES. 12 



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



glumes). Order 13. POALES. 15 



Perianth of 2 distinct series, the inner series usually corolloid. 



Gynoecium of distinct carpels. Order u. ALISMALES. 13 



Gynoecium of united carpels. 



Endosperm mealy. Order 15. XYRIDALES. 75 



Endosperm fleshy, horny or cartilaginous. 



Ovary and fruit superior. Order 16. LILIALES. 76 



Ovary and fruit wholly inferior or half-inferior. 



Endosperm present and usually copious ; flowers regular ; androe- 



cium not reduced. Order 17. AMARYLLIDALES. 86 



Endosperm wanting. 



Flowers regular, monoecious or dioecious : aquatic plants. 



Order 12. HYDROCHARITALES. 15 

 Flowers irregular, perfect: terrestrial or epiphytic plants. 



Order 18. ORCHIDALES. 87 



2. DlCOTYLEDONES. 



A. Corolla wanting. 



I. Calyx wanting, at least in the staminate flowers. 



Herbs. Order 30. EUPHORBIALES. 221 



Trees or shrubs. 



Fruit i -seeded: seeds without tufts of hairs. 



Fruit a nut or an achene. Corylaceae in Order 20. FAGALES. 96 



Fruit a drupe or a samara. Oleaceae in Order 41. OLEALES. 264 



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



Order 19. SALICALES. 91 



II. Calyx present at least in the staminate or in the perfect flowers. 



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



a nut or an achene. Order 20. FAGALES. 96 



2. Flowers, at least the staminate, not in aments. 

 a. Ovary superior. 



Gyncecium of i or several and distinct carpels : stigma and style 



of each solitary. 

 Carpel solitary. 



Ovary neither enclosed nor seated in a hypanthium or a calyx- 

 tube. 

 Flowers not solitary in the axils of the leaves ; land plants. 



Urticacese in Order 21. URTICALES. 99 

 Flowers solitary in the axils of the leaves ; aquatic plants. 



Ceratophyllacese in Order 25. RANALES. 134 

 Ovary enclosed in or seated in a hypanthium or a calyx-tube. 

 Stamens borne under the gynoecium. 



Allioniaceae in Order 24. CHENOPODIALES. 122 

 Stamens borne on the hypanthium or adnate to the calyx- 

 tube- Order 36. THYMELEALES. 239 

 Carpels several. 



