EXOGENOUS OR DICOTYLEDONOUS PLANTS. 461 



Calyx corolline, double. Stamens perigynous. Basei,i,ace;h. 



Calyx not corolline : no scarious bracts. Chenopodiace.«, 



Calyx and bracts scarious, sometimes colored. Amarantacb^. 



Stipules sheathing. Calyx corolline. Ovule orthotropous. PoLYGONACEiE. 



Group 4. Flowers perfect, polygamous or dicEcious, not disposed in aments, 

 with a regular and often petaloid calyx. Style or stigma one. Ovary 

 one-celled, with one or few ovules : but the fruit one-celled and one-seeded. 

 Embryo not coiled around albumen. — Trees or shrubs, rarely herbs. 



Calyx free from the ovary, and not enveloping the fruit. 



Flowers polygamo-dioecious. Anthers opening by valves. Laukace.ie. 



Flowers perfect. Anthers opening longitudinally. Thymelace.^;. 



Calyx free, but baccate in fruit and enclosing the achenium. Eleagnace.*;. 

 Calyx adnate to the ovary. Ovule destitute of coats. 



Ovules several, pendulous from a stipe-like placenta. Santalace^. 



Ovule solitary, suspended- Parasitic shrubs. LoRANTHACEiE. 



Group 5. Flowers perfect, in spikes which often appear like aments, achlamyde- 

 ous. Ovaries solitary or several, with one or few erect or ascending 

 orthotropous ovules. Embryo minute, enclosed in a persistent embryo-sac 

 at the apex of the albumen. — Herbs or shrubby plants, with tumid nodes. 



Ovaiy one, one-ovuled. Stipule opposite the leaf or none. Piperace.«. 



Ovaries more than one. Stipules, when present, in pairs. Saururace.*. 



Group 6. Flowers perfect or diclinous, frequently destitute of both calyx and 

 corolla. — Submersed or floating aquatic herbs. 



Flowers monoecious. Fruit one-celled, one-seeded. CERATOPHTLLACE.ffi. 



Flowers mostly perfect. Fruit four-celled, four-seeded. Callitrichace^. 



Flowers mostly perfect. Pod several-celled, several-seeded. Podostemace.s;. 



Group 7. Flowers moncecious or dioecious, not amentaceous. Fruit capsular 

 or drupaceous, with two or more cells, and one (or rarely two) seeds in 

 each cell. Embryo straight in the axis of the albumen. — Herbs, shrubs, 

 or trees. 



Fruit mostly di-y. Juice milky. Pollen simple. Eitphorbiace^,. 



Fruit drupaceous. Pollen compound ; the grains in fours. Emfetrace^e. 



Group 8. Flowers monoecious, dioecious, or polygamous, with a regular calyx 

 which is free from the one-celled (or rarely two-celled) ovary and one- 

 seeded fruit (achenium, drupe, or samara), but sometimes enclosing it. 

 Embryo curved, or straight, with the radicle superior, in albumen wheu 

 there is any. — Inflorescence various, often in spikes, heads, or a sort of 

 aments. URTioACE.a;. 



Group 9. Flowers monoecious or dioecious, the sterile, and frequently the fertile- 

 also, in aments, or in heads or spikes. Calyx of the fertile flowers, if any, 

 adherent. Ovary often two- to several-celled, but the fniit always one- 

 celled. — Trees or shrubs. 



