KEY TO THE ORDERS. XIX 



CONVOLVULACE.E. Style 2-cleft. Pod 2-celled. generally 

 4-seeded ; seeds large. Chiefly twining or trailing 

 plants 173 



SOLAXACE^E. Style single. Pod or berry 2-celled, many- 

 seeded 174 



* * * * Stamens fewer than the lobes of the corolla ; the 

 corolla mostly irregular or %-lipped, 



LABIAT^E. Ovary 4-lobed around the base of the style. 



Stamens 4 and didynamous, or occasionally only 



2 with anthers. . Stem square 160 



VERBENACE^S. Ovary 4-celled, but not lobed ; the style 



rising from the apex. Or, Ovary 1 -celled and 1- 



seeded. Stamens didynamous 158 



LENTIBULARTACE.E. Aquatics. Stamens 2. Ovary 1- 



celled, with a free central placenta 149 



OROB.YNCHACE^E. Parasitic herbs, without green foliage. 



Ovary 1 -celled, with many seeds on the walls. 



Stamens didynamous 150 



SCROPHULARIACE.E. Ovary 2-celled, with many seeds. 



Stamens didynamous, or only 2 151 



ACANTHACE^E. Stamens 2, the anther-cells separated. 



Ovary flat, 2-celled, 4-seeded. Aquatics 159 



III. APETALOUS DIVISION. 



Corolla (and sometimes calyx also) wanting. 



A. Flowers not in catkins. 



* Calyx and corolla both wanting. 



PIPERACE^E. Flowers white, in a dense terminal spike, 

 nodding at the end. Carpels 6 or 4, nearly separ- 

 ate 182 



CERATOPHYLLACE.E. Immersed aquatics, with whorled 



finely dissected leaves. Flowers monoecious .... 213 



.* * Calyx superior (i.e., adherent to the ovary ). 



SAXIFRAGACE.E. Small, smooth herbs, with inconspicuous 

 greenish-yellow flowers. Stamens twice as many 

 as the calyx-lobes, on a conspicuous disk 75 



HALORAGE^E. Aquatics. Leaves finely dissected or linear. 



Stamens 1-8. Ovary 3-4-lobed or (Hippuris)l -celled. 79 



ONAGRACE^E. Herbs, in ditches. Stamens 4. Ovary 4- 



celled, 4-sided. ^. 8! 



