GENEBAL. KEY. iii 



Shrubs with scurfy leaves; flowers mostly dioecious. 



Elaeagnaceae in THYMELEALES 229 



Herbs, with the calyx colored like a corolla. 

 Leaves opposite, simple. 



Nyctaginaceae in CHENOPODIALES 132 



Leaves alternate, pinnate Sanguisorba in ROSALES 178 



Ovary plainly free from the calyx, which is sometimes wanting. 

 Stipules sheathing the stem at the nodes. 



Trees, calyx none; flowers monoBcious, in heads. 



Platanaceae in ROSALES 167 

 Herbs: calyx present and commonly petal-like. 



POLYGONALES 128 

 Stipules not sheathing the stem, or none. 

 Aquatic herbs, submerged or nearly so. 



Leaves whorled and dissected; style single. 



Ceratophyllaceae in EANALES 143 

 Leaves opposite, entire; styles 2; ovary 4-celled. 



Halokagidaceae in MYRTALES 230 

 Not aquatic herbs. 



Ovary 10-celled; berry 10-seeded. 



Phytolaccaceae in CHENOPODIALES 132 

 Ovary 3- (rarely 1-2-) celled; juice usually milky. 



Buphorbiaceae in GERANIALES 205 

 Ovary 1-celled; juice not milky. 



Style, if any, and stigma only 1; leaves simple; no 



scarious bracts around the flowers . . . URTICALES 124 

 Styles or stigmas 2 or 3; embryo coiled or curved. 

 Stipules not scarious; leaves palmately cleft or 

 palmately compound. 



Cannabis and Humulus in URTICALES 1S6 

 Stipules scarious or none . . . CHENOPODIALES 132 

 Shrubs or trees. 



Ovules, a pair in each cell of the ovary. 

 Fruit 2-celled, a double samara. 



Aceraceae in SAPINDALES 214 

 Fruit a 1-celled and 1-seeded samara or a drupe. 



Oleaceae in GENTIANALES 253 

 Ovules single, in each cell of the 



Three-9-celled ovary; leaves heath-like. 



Empetraceae in SAPINDALES 214 

 Three-celled ovary; leaves broad. 



Rhamnaceae in RHAMNALES 218 

 One-2-eelled ovary; styles or stigmas 2-cleft. 



URTICALES 124 

 One-celled ovary; style and stigma single and entire. 

 Anthers opening longitudinally. 



Thymeleaceae in THYMELEALES 229 

 Anthers opening by uplifted valves. 



Latjraceae in RANALES 143 



B. Flowers monoecious or dioecious, one or both sorts in catkins. 



1. Only one sort of flowers in catkins or catkin-like heads. 



Fertile flowers in a short catkin, head or strobile URTICALES 124 



Fertile flowers single or clustered; sterile in slender catkins (except 



Leaves pinnate; fertile flowers and fruit naked. . JUGLANDALES 118 

 Leaves simple; fertile flowers 1-3 in an involucre or cup. 



2. Both sterile and fertile flowers in catkins or catkin-like heads. 

 fWao-v and cod 2-celled, many-seeded Liquidambar in ROSALES 171 



