xxxvii 



97 



97a. Perianth with but one circle of floral leaves 98. 

 97b. Perianth consisting of both calyx and corolla 101. 



98a. Flowers small, in dense heads subtended by conspicuous 



bracts 99. 

 98b. Flowers 2 5, in a colored spreading 5-lobed involucre 



NYCTAGINACEAE, p. 31. 

 98c. Flowers in various sorts of clusters or solitary, but never 



in heads with a conspicuous involucre 100. 



99a. Bracts 4, white and conspicuous; stem not thorny 



4a, in CORNACEAE, p. 83. 

 99b. Bracts green; stem thorny DIPSACACEAE, p. 112. 



lOOa. Stamens 3 VALERIAN ACE AE, p. 111. 



lOOb. Stamens 4 or 5 RUBIACEAE, p. 108. 



lOla. Anthers more numerous than the lobes of the corolla 102. 

 lOlb. Anthers just as many as the lobes of the corolla 103. 

 lOlc. Anthers fewer than the lobes of the corolla 110. 



102a. Leaves simple POLYGALACEAE, p. 65. 



102b. Leaves compound with 3 leaflets OXALIDACEAE, p. 64. 

 102c. Leaves finely dissected; stems climbing 



2a, in FUMARIACEAE, p. 41. 

 103a. Ovaries 2 104. 

 103b. Ovary 1, but very deeply 4-lobed, with a single style 



LABIATAE, p. 95. 

 103c. Ovary 1, not deeply lobed 105. 



104a. Stamens united, surrounding and more or less concealing 

 the ovaries, and not resembling ordinary stamens 



ASCLEPIADACEAE, p. 90. 

 104b. Stamens separate, of ordinary structure 



APOCYNACEAE, p. 90. 



105a. Ovary inferior, appearing as a swelling below the calyx at the 



apex of the pedicel 106. 

 105b. Ovary superior, located in the center of the flower 107. 



106a. Corolla 3 4-lobed RUBIACEAE, p. 108. 



106b. Corolla 5-lobed 3b, in CAPRIFOLIACEAE, p. 109. 



107a. Leaves toothed or deeply cut VERBEtfACEAE, p. 99. 



107b. Leaves entire 108. 



108a. A stamen in front of the middle of each petal 



PRIMULACEAE, p. 87. 



108b. Stamens located between the petals or lobes of the corolla, 

 or else so far down in the tubular corolla that their position is 

 not easily ascertained 109. 



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