106 



KEY TO THE FAMILIES AND GENERA 



6. Helianthus Tribe. 



Subtribe 1. MELAMPODIE-E. Rays pistillate; disk-fls. staminate: 

 achenes usually with coriaceous or thicker pericarp: style mostly 

 entire; receptacle chaffy throughout; pappus none. 



A. Involucre of the many-fld. heads broad; 

 inner bracts concave, embracing and half 

 inclosing the thick, turgid, obovoid achenes.. 60. Polymnia. 

 AA. Involucre broad, of plane or barely concave 

 bracts ; innermost subtending obcom- 

 pressed achenes, but not inclosing nor em- 

 bracing them. 

 B. Rays, or rather their ovaries and achenes, 



in more than 1 series ................... 61. Silphium, 



BB. Rays and achenes in a single series. 



c. Heads nearly discoid or rays short ........ 62. Partkenium. 



cc. Heads conspicuously radiate, mostly of 



5 fertile and rather numerous sterile fls. . 63. Chrysogo- 



[num. 



Subtribe 2. AMBHOISK.*;. Pistillate fls. apetalous, or with 

 corolla reduced to a tube or ring around base of 2-parted style; 

 staminate fls. with 4-5-lobed corolla; anthers slightly united or 

 free; style abortive, hairy only at the somewhat enlarged and 

 depressed summit. 



A. Herbs: heads of 2 kinds, the fertile with a 



bur-like involucre ....................... 64. Ambrosia. 



AA. Shrubs: heads all alike ..................... 65. Iva. 



Subtribe 3. ZINNIE^E. Rays pistillate; the tube absent or very 

 short, persistent on achene and at length papery; disk-fU. 

 bisexual, rarely sterile, subtended or embraced by chaffy bracts: 

 Ivs. opposite. 



A. Receptacle flattish ....... . ................ 66. Sanvttalia. 



AA. Receptacle conical, cylindrical or elongated. 



B. Achenes, at least inner ones, 1-3-awned ..... 67. Zinnia. 



BB. Achenes without pappus ................. 68. Heliopsis. 



Subtribe 4. VERBESINE^E. Rays pistillate, or neutral, becom- 

 ing papery and persistent; disk-fls. bisexual; anthers often blackish: 

 achenes various, but those of disk never obcompressed : pappus 

 various. 



A. Chaff of receptacle permanently investing 



achenes as an accessory covering ........... 69. Sclerocarpus. 



AA. Chaff of receptacle concave or complicate, 

 loosely embracing or subtending the disk- 

 achenes, mostly persistent. 



B. Rays sometimes absent. Certain species of.. 70. Spilanthes. 

 BB. Rays usually present. 



c. Receptacle high, from conical to colum- 



nar or subulate, at least in fr. 

 D. The rays, if present, pistillate ........ 70. Spilanthes. 



DO. The rays sterile. 



E. Color of rays rose or rose-purple. . . . 71. Echtnacea. 



EE. Color of rays yellow or partly brown- 



purple (sometimes wholly so). 

 F. Achenes 4-angled, prismatic ...... 72. Rudbeckia. 



FF. Achenes short and broad, com- 



pressed ....................... 73. Lepachy/8. 



cc. Receptacle low, flat to convex, rarely be- 



coming conical. 



D. Achenes not winged nor very flat, when 

 flattened not margined nor sharp- 

 edged. 

 E. Rays pistillate .................... 74. Balsamor- 



EE. Rays sterile. [rhiza. 



F. Achenes pubescent .............. 75. Viguiera. 



FF. Achenes glabrous ................ 76. HelianthuR. 



DO. Achenes of the ray or margin often 

 triquetrous, of the disk either flat- 

 compressed and margined or thin- 

 edged, or if turgid some of them 

 winged. 



E. Rays neutral. 



F. Pappus 0, or an awn or its 

 rudiment answering to each 

 margin of the wingless achene. ...77. Encelia. 



FF. Pappus of delicate squamelUe be- 

 tween the 2 chaffy teeth or awns 

 which surmount the 2 acute 

 margins of the achene .......... 78. Helianthella. 



FFF. Pappus of 2 slender-subulate 

 naked awns, at length divergent, 

 sometimes with 2 or 3 inter- 

 mediate awns ................. 79. Actinomeris 



EE. Rays pistillate, rarely neutral in 



V crbesina. 

 r. Pappus of co distinct squamelUe.. . .80. Paacalia. 



FF. Pappus of dilated awns or 2 awn- 

 like paleee on the angles of the 

 achene, with 2 small intermediate 



Subtribe 5. COREOPSIDEVG. Rays pistillate or neutral; disk- 

 fls. fertile; receptacle chaffy; chaff flat or hardly concave: achenes 

 more or less dorsally compressed, often 2-awned. 



A. Involucral bracts distinct, the outer herbace- 

 ous, inner somewhat like palese 83. (iuizotia. 



AA. Involucre double; inner bracts membran- 

 ous, subequal, connate at base or often 

 higher; outer bracts few and small or 

 minute. 



B. Plants are all climbers with pistillate rays, 

 achenes much enlarging and sterile 



disk-fls. with individed style 84. ffidalyoa. 



BB. Plants not climbing: rays usually sterile, 

 c. Style-branches with long hairy appen- 

 dages 85. Dahlia. 



cc. Style-branches truncate, penicillate or 



with short appendages. 

 o. Bracts of inner involucre united into a 



cup 86. Theles- 



DD. Bracts of involucre distinct, or united [perma. 



only at the common base. 

 E. Achenes beaked, slender: rays purple 

 or rose, in 1 species yellow; white 

 vars. in cult. : awns mostly 



deciduous 87. Cosmos. 



EE. Achenes not beaked: rays yellow or 



white. 

 F. Tube of disk-fl. without ring at top. 



Q. Lvs. or divisions entire 88. Coreopsis. 



QG. Lvs, or divisions serrate 89. Bidens. 



FF. Tube of disk-fls. with a ring near 



the top 90. Leptosyne. 



Subtribe 6. GALIXSOGE.E. Heads rayless and homogamous 

 (inMarshallia). Pappus of distinct palete 91. Marshallia. 



Subtribe 7. MADIL.E. Rays pistillate, each subtended by an 

 involucral bract which partly or completely incloses its achene; 

 disk-fls with both stamens and styles, but some or all sterile: 

 glandular, viscid and heavy-scented herbs. 



A. Achenes laterally compressed 92. Madia. 



AA. Achenes not laterally compressed 93. Layia, 



7. Helenium Tribe. 



A. Involucral bracts united nearly throughout 



into an oblong cup or tube 94. Tagetes. 



(See also Lasthenia.) 



A A. Involucral bracts hardly at all imbricated; 

 when broad, nearly equal or in 1 series. 



B. Receptacle mostly high-conical, and acute, 

 beset after the achenes have fallen 

 projecting points (as if pedicels on wh 



by 



ich 



...... 



FF. Pappus of 2 awns, sometimes 1-3 [ium, 



orO, and no intermediate squam- 



melUe ........................ 82. Verbesina. 



they were inserted). 

 c. The involucre a single series of bracts 

 connate by their edges into a 5-15- 



toothed green cup 95. Lasthenia. 



cc.The involucre of loose, distinct bracts 96. Bseria 



(Also Actinolepis coronaria. ) 

 BB. Receptacle flat or convex, rarely obtusely 

 conical: achenes from linear to obpyram- 

 idal, rarely 5-angled. (See also BBS.) 

 c. Herbage mostly woolly: involucral bracts 



erect, not membranous 97. Eriophyl- 



cc. Herbage usually not woolly. [Ium. 



D. Disk-fls. deeply 5-cleft: involucral 



bracts mostly appressed 98. Polypteria. 



DO. Disk-fls. with long and narrow throat 

 and 5 short lobes or teeth. 



E. Heads solitary 99, Hidsea* 



EE. Heads paniculate or corymbose. 

 F. Plants tomentose herbs, the Ivs. 



dissected. 



a. Involucral bracts free, narrow. .100. Chtenactia. 

 GO. Involucral bracts connected at 



the base, broad and obtuse. . . . 101. BaHa. 

 FF. Plants not tomentose, the Ivs. not 



dissected 102. Pericome. 



BBS. Receptacle from convex to oblong: achenes 

 short, obpyramidal or top-shaped, 5-10- 

 ribbecl or angled, mostly silky hairy : 

 disk-fls. all fertile. 



c. The receptacle destitute of awn-like 

 fimbrillfiD among the fls. 



D. Involucre erect or nearly so 103. Actinella. 



DD. Involucre spreading or soon reflexed. . . . 104. Helenium. 

 cc. The receptacle beset with bristle-like or 

 awl-shaped or rarely dentiform fimbrillffi 

 among the fls 105. QaiUardia. 



8. Anthemis Tribe. 



A. Receptacle chaffy. , 



B. Heads usually discoid. 



c. Shrubs with small, closely clu.stered Ivs... 106. Erioceph- 

 cc. Herbs, or sometimes slightly shrubby. [a Jus. 



o. Corolla with a hood-like appendage at 



base 107. Santolina. 



DD. Corolla without such appendage 108. Lonas. 



