1150 



CARDUACEAE 



** Receptacle flat or convex. 



Achenes of the disk neither sharp-edged, margined 

 nor winged. 

 Ray-flowers fruit-producing. 



Achenes turgid, those of the disk obtusely if 

 at all angled : stems herbaceous. 

 Pappus of several scales partially united 



into a constricted cup or ring. 

 Pappus of several distinct scales, sometimes 

 accompanied by 2 short awns. 

 Achenes acutely 4-angled, or 3-angled in the 

 ray : stems woody. 

 Ray-flowers not fruit-producing, rarely wanting. 

 Pappus of 2 chaffy awns or scales, one over 

 each main angle of the achene, or occa- 

 1 sionally of 1 or 2 more awns, and of 2 or 



more intermediate truncate scales on 

 ^ each side. 



Pappus of 2 scarious acute or awned scales, 



without intermediate scales, except morei 



or less detached portions of their bases. 



Achenes of the disk thin-edged, margined or winged. 



Ray-flowers neutral (rarely wanting) : achenes 



wingless or essentially so, sometimes vil- 



lous-ciliate. 



Pappus wanting, or an awn to each margin of 



the achene. 

 Pappus of scales between the 2 or more awns 

 or teeth over each angle of the achene. 

 Ray-flowers fruit-producing, or sometimes neu- 

 tral in Verbesina (rarely wanting) : achenes, 

 at least some of them, wing-margined. 

 Pappus-awns connected by dilated bases or 

 with intermediate°distinct or confluent 

 scales. 

 Ray-flowers fruit-producing. 

 Ray-flowers neutral or wanting. 

 Pappiis-awns without intermediate scales, 

 sometimes obsolete. 

 Involucre flat ; bracts elongated, spreading: 



annual herbs. 

 Involucre campanulate or hemispheric ; 

 bracts short, erect or appressed : per- 

 ennial herbs, 

 b. Achenes markedly flattened parallel with the involucral bracts. 

 Involucre single. 



Marginal fruit wingless. 

 Marginal fruit winged. 

 Involucre double. 



Bracts of the involucre distinct. 



Pappus of 2 fimbriolate awns, scales or teeth or a mere bor- 

 der, or wanting. 

 Pappus of 2-6 awns or teeth, upwardly or downwardly 

 barbed or hispid. 

 Achenes beakless : ray-flowers with yellow or white lig- 



ules, or wanting. 

 Achenes beaked : ray-flowers with purple or rose ligules. 

 Bracts of the inner involucre partially united. 

 B. Pappus of numerous scales. 



Receptacle honeycombed bv the concretion of the bractlets, 



Pits of the receptacle with truncate edges : head solitary: ray- 

 flowers 20-30. 

 Pits of the receptacle with subulate-toothed edges : heads corym- 

 bose : ray-flowers 8-10. 

 Receptacle with distinct bractlets. 

 Ray-flowers wanting. 

 Ray-flowers present. 



Pappus-scales entire or fimbriate. 

 Paijpus-scales plumose-ciliate. 



Tribe VI. HELENIEAE. 

 A. Plant-tissues without oil glands. 

 Leaf-blades or leaf-segments terete. 

 Leaf-blades or leaf-segments flat. 



Bracts of the involucre petal-like, pale or colored, at least the margins 

 and tips, scarious. 

 Corollas with ovate or oblong lobes. 



Involucres of a broadly campanulate type or hemispheric : stig- 

 mas with short coiiic appendages. 

 Involucre of a turbinate-canipanulate type : stigmas with atten- 

 uate-subulate appendages. 

 Corollas with linear lobes. 

 Bracts of the Involucre narrow, herbaceous. 

 a. Receptacle naked. 



* Bracts of the involucre appressed. 



Achenes terete or 4-10-angled or merely 4-10-ribbed. 

 Achenes 4-angled. 



Bracts of the involucre linear or nearly so, more or less 

 embracing the approximate achenes. 



92. Stemmodontia. 



93. Pascalia. 



94. borrichia. 



95. ViGUIERA. 



96. Helianthus. 



97. Encelia. 



98. Helianthella. 



99. Zexmenia. 

 100. actinomeris. 



101. Verbesina. 



102. Ximenesia. 



103. Synedrella. 



104. Calyptrocarpus. 



105. Coreopsis. 



106. Bidens. 



107. Cosmos. 



108. Thelesperma. 



109. Endorima. 



110. actinospermum. 



111. Marshallia. 



112. Galinsoga. 



113. Tridax. 



114. Clappia. 



115. Hymenopappus. 



116. Florestina. 



117. Polypteris. 



118. PAL.iFOXIA. 



