viii KEY TO THE ORDERS 



b. Trees or shrubs, with pinnately or palmately compound or lobed leaf-blades : ovules 



solitary in each cavity of the ovary. Order ARECALES. 221 



B. Ovary, and fruit, wholly inferior or half-inferior. 

 Endosperm present and usually copious. 



Flowers regular : androecium not reduced. Order AMARYLLIDALES. 285 



Flowers very irregular : androecium much reduced and modified. 



Order SCITAMINALES. 307 

 Endosperm wanting. 



Flowers regular, monoecious or dioecious : aquatic plants. Order HYDROCHARITALES. 46 

 Flowers irregular, perfect : terrestrial or epiphytic plants. Order ORCHIDALES. 308 



2. DlCOTYLEDONES. 



A. Corolla wanting, except in the pistillate flowers ofJuglans (Juglandaceae). 



Calyx wanting, at least in the staminate flowers, except sometimes in Casuarina (Casuarinaceae) . 

 Herbs. 



Flowers mainly perfect. 



Seeds solitary in each carpel or in each cavity of the ovary : endosperm present. 



Flowers spicate : styles wanting : stigmas sessile. Order PIPERALES. 330 



Flowers axillary : styles present. Callitrichaceae in Order EUPHORBIALES. 690 



Seeds numerous in each cavity of the ovary : endosperm wanting. 



Podostemaceae in Order ROSALES. 494 



Flowers monoecious or dioecious. Order EUPHORBIALES. 690 



Trees or shrubs : flowers monoecious or dioecious, or polygamous. 



Leaves represented by appressed whorled scales : stems or branches loosely jointed. 



Order CASUARINALES. 331 



Leaves not appressed scales : stems or branches not loosely jointed. 

 Fruit 1-seeded : seeds without tufts of hairs. 



Ovules 1 or 2 in each cavity of the ovary : flowers not in heads. 



Gynoecium 1-carpellary : stigma 1 : ovule laterally attached and amphitropous. 



Order LEITNERIALES. 336 

 Gynoecium 2-carpellary : stigmas 2 : ovule erect and orthotropous or pendulous 



and anatropous. 

 Pistillate flowers without a calyx : ovule erect and orthotropous. 



Order MYRICALES. 336 



Pistillate flowers with a calyx : ovule pendulous and anatropous. 

 Leaf-blades simple. 



Fruit a nut or an achene. Corylaceae in Order FAGALES. 343 



Fruit a drupe. Oleaceae in Order OLEALES. 916 



Leaf-blades compound : fruit a samara. Oleaceae in Order OLEALES. 916 



Ovules many : flowers aggregated into dense heads. Altingiaceae in Order ROSALES. 494 



Fruit many-seeded : seeds each with a tuft of hairs. Order SALICALES. 338 



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



Leaves represented by appressed whorled scales : branches loosely jointed. 



Order CASUARINALES. 331 

 Leaves not appressed scales : branches not loosely jointed. 



Flowers, at least the etaminate, in aments, or ament-like spikes. 

 Leaf-blades simple : ovule pendulous and anatropous. 



Pistillate flowers separate at maturity : fruit a nut or an achene. Order FAGALES. 343 

 Pistillate flowers forming aggregate fruits : fruit drupe-like. 



Artocarpaceae in Order URTICALES. 355 



Leaf-blades pinnately compound : ovule erect and orthotropous. Order JUGLANDALES. 332 

 Flowers, at least the staminate, not in aments. 

 a. Ovary superior. 



Gynoecium of 1 or several and distinct carpels : stigma and style solitary. 

 Carpel solitary. 



Style lateral and oblique. Petiveriaceae in Order CHENOPODIALES. 383 



Style axile, erect. 



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

 Flowers not solitary in axils : land plants. 



Filaments free and distinct. Urticaceae in Order URTICALES. 355 



Filaments adnate to the sepals or to the calyx-tube. 



Order PROTEALES. 817 

 Flowers solitary in axils ; aquatic plants. 



Ceratophyllaceae in Order RANALES. 428 

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

 Stamens borne under the gynoecium. 



Allioniaceae in Order CHENOPODIALES. 383 

 Stamens borne on the hypanthium or adnate to the calyx-tube. 



Order THYMELEALES. 818 

 Carpels several : 



Stamens inserted below the ovary. Families in Order RANALES. 428 



Stamens inserted on the edge of a cup-shaped hypanthium. 



Rosaceae in Order ROSALES. 494 



Gynoecium of 2 or several united carpels : stigmas or styles 2 or several. 

 * Ovary, by abortion. 1-celled and 1-ovuled. 



Leaves with sheathing stipules (ocreae). Order POLYGONALES. 366 



Leaves estipulate, or if stipules are present they are not sheathing. 

 Trees or shrubs. 



Anthers opening by slits : ovary not seated in a hypanthium. 



Ulmaceae in Order URTICALES. 355 



Anthers opening by hinged valves : ovary seated in an accrescent hypan- 

 thium. Lauraceae in Order THYMELEALES. 818 

 Herbs or vines. 



t Leaves with stipules. 



Stipules herbaceous : inflorescence spicate or racemose : leaf-blades 



palmately veined. Cannabinaceae in Order URTICALES. 355 



