776 coMPOSiTAE (composite family) 



♦ ♦ ♦ * Pappus composed entirely of capillary bristles, not plumose. 

 +- Achenes strongly muricate or spiuulose above. 

 97. Chondrilla. Stem branching, leafy. Involucre few-flowered, calyculate. Achenes terete, 



several-ribbed. 

 9i Taraxacum. Scapose. Involucre cal3-culate, many-flowered. Achenes fusiform, 4-5-ribbed. 

 +- +- Achenes not muricate above. 

 ♦+ Achenes flat or flattish. Pappus white, fine and soft. Involucre imbricated. Leafy-stemmed, 

 with panicled heads. 

 99. Sonchus. Achenes flattish, not at all beaked. Flowers 50 or more in each head, yellow. 



100. Lactuca. Achenes usually more or less beaked. Flowers 6-30 in each head, yellow, blue, 



or purple. 



++ ++ Achenes columnar, often slender. 



= Achenes not conspicuously narrowed at base. Flowers rose or purple. 



101. Lygodesmia. Achenes long, slightly tapering above. Pappus white. Stems nearly leafless; 



Head erect. Western, 



= = Achenes narrowed at base. 

 a. Achenes beaked (sometimes beakless in no. 102); flowers yellow. 



102. Agoseris. Scapose. Involucre loosely imbricated. Achenes 10-ribbed. 



103. Pyrrhopappus. Scapose or branched. Achenes 4-5-ribbed. 



b. Achenes not beaked. 

 1. Involucral bracts in a single row. 



104. Crepis. Pappus white, soft. Flowers yellow or orange. 



2. Bracts in more than one row. 



105. Prenanthes. Involucre calyculate. Achenes short, blunt. Pappus whitish, tawny, or 



brown. Flowers white, cream-color, or pinkish. 



106. Hieracium. Involucre imbricated. Pappus tawny. Flowers yellow or orange. 



Artificial Key to Genera 

 Series I. Disk-flowers with tubular regular corollas ; ligulate 



FLOWERS IP present MARGINAL. 



§ 1. Bays or ligulate flowers none; corollas all tubular (or rarely none). 



* Flowers of the head all perfect and alike a. 



a. Pappus composed of bristles b. 



b. Pappus double, the outer of very short, the inner of longer bristles . 1. Vernonia. 

 b. Pappus simple, the bristles all of the same sort c, 

 c. Heads few-flowered, themselves aggregated into compound or 



dense clusters . • 2. Elephantopus. 



e. Heads separate d. 

 d. Receptacle (when the flowers are pulled ofl") bristly-hairy. 



Leaves not prickly 80, Arctium. 



x.eaves prickly. 



Filaments glabrous, united into a tube 85. Silybum. 



lilaments papillose-pilose, separate. 



Pappus-bristles not plumose 82. Carduus. 



Pappus-bristles plumose 83. Cirsium. 



d. Eeceptacle deeply honeycomb-like ..,,.,. 84. Onopordum. 

 d. Eeceptacle naked. 



Pappus-bristles plumose. 

 Corollas rose-color or purple; heads racemose or spicate . 9. Liatria. 



Corollas whitish ; heads corymbose 8. Kuhnia. 



Pappus-bristles sometimes roughened but not plumose. 

 Stem twining ; leaves opposite, triangular-hastate . , 5. Mikaiiia. 



Stem not twining. 



Achenes 5-angled, 5-ribbed 4. Eupatorium. 



Achenes 8-10-ribbed or without definite angles or ribs. 



Annual 77. Erechtitea. 



Perennial. 

 Flowers yellow. 

 Involucral bracts much imbricated in several series . 18, Bigelowia. 

 Involucre simple oi* merely calyculate • . .79. Serucio. 



