38(37). Corolla lobes usually convolute in bud; capsule elastically dehiscent, the 

 seeds ballistically ejected at dehiscence 122. Acanthaceae, p. 1525 



38. Corolla lobes usually imbricate or valvate in bud; capsule not elastically de- 



hiscent (or fruit a samara in some taxa), the seeds not ballistic (39) 



39(38). The 2 stamens opposite each other or at least widely separated on the 

 nearly aotinomorphic corolla 106. Oleaceae, p. 1301 



39. The 2 or 4 stamens not widely separated in the usually strongly zygomorphic 



corolla 119. Scrophulariaceae, p. 1456 



40(33). Only a single seed maturing in each flower 



103. Plumbaginaceae, p. 1295 



40. At least 2 and commonly more seeds produced by each flower (41 ) 



41(40). Placenta obviously free-central, attached at base of the single cell of 



the ovary; stamens opposite the corolla lobes 



102. Primulaceae, p. 1276 



41. Placenta axile or parietal, or if basal then the ovary with more than 1 cell, 



or if placentation difficult to determine at least not obviously free- 

 central; stamens alternate with the corolla lobes (but this very 

 obscure in some flowers) (42) 



42(41). Ovary 3-celled; style usually 3-cleft at apex; plant never twining; sepals 

 united by translucent webbing tissue....! 12. Polemoniaceae , p. 1369 



42. Ovary usually 2- or 4-celled, rarely 1-celled (43) 



43(42). Placentae parietal (but often intruded deeply into the chamber and 

 meeting at the center, their parietal nature then revealed only by 

 very careful dissection); seeds small and numerous; anthers after 

 anthesis shriveling into a spiral or helix; leaves opposite (except in 



genus Nymphoides); cymes never scorpioid 



108. Gentianaceae, p. 1312 



43. Placentae axile or axile-basal (except parietal in some Hydrophyllaceae with 



scorpioid cymes and more than 1 stigma); seeds few to numerous; 

 anthers after anthesis not shriveling into a spiral or a helix; leaves 

 opposite or alternate (44) 



44(43). Fruit drupaceous or a deeply lobed schizocarp of 2 to 4 achenelike 

 mericarps ...114. Boraginaceae, p. 1383 



44. Fruit a capsule or berry (45) 



45(44). Each flower with a single (sometimes shallowly 2-lobed) stigma (46) 



45. Each flower with 1 or 2 styles and at least 2 stigmas (47) 



46(45). Herbs or shrubs; leaves alternate (sometimes fascicled): flowers almost 



exclusively radially symmetrical; fruit a capsule or berry 



118. Solanaceae, p. 1449 



46. Opposite-leaved herbs with strongly zygomorphic corollas; fruit a capsule.... 



119. Scrophulariaceae, p. 1456 



47(45). Often herbaceous twining vines or rhizomatous or stoloniferous creep- 

 ing herbs; flowers usually solitary from the axils; ovary usually 2- 

 or 3- or 4-celled 111. Convolvulaceae, p. 1350 



47. Never twining, usually small erect taprooted herbs; flowers in cymes or heli- 



coid or scorpioid cymes, or solitary; ovary usually 1-celled (2- 

 celled in Nama) 113. Hydrophyllaceae, p. 1375 



48(1). Completely submerged fresh-water aquatics with much-reduced flowers 

 and very peculiar habits (cf. also Haloragaceae and Lemnaceae) 

 (49) 



27 



