KEY TO THE ORDERS. XIX 



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

 4-seeded ; seeds large. Chiefly twining or trailing 

 plants 173 



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

 seeded 174 



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

 corona mostly irregular or 2-lipped. 



LABIATE. Ovary 4-lobed around the base of the style. 



Stamens 4 and didynamous, or occasionally only 



2 with anthers. Stem square 160 



VriRBENACEjE. Ovary 4-celled, but not lobed ; the style 



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



seeded. Stamens didynamous 158 



LENTIBULARIACE^E. Aquatics. Stamens 2. Ovary 1- 



celled, with a free central placenta 149 



OROBANCHACE^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.*. 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.S:. 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 ). 



SAXIFRAACE^B. Small, smooth herbs, with inconspicuous 

 greenish-yellow flowers. Stamens twice as many 

 as the calyx-lobes, on a conspicuous disk 75 



HALO RAG E.I:. 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 81 



