THISTLE FAMILY 633 
Fruit of disk flowers 4-sided, without margins . Rudbeckia 
Fruit of disk flowers flat, with margins . . . . Ratibida 
Ray flowers not fruit-producing, receptacle flat or conve», not high. 
Leaves (opposite Tie Se os Se ee Bfelianthus 
Leaves (in our species) alternate . Verbesina 
Aigrette of 2 or more scales, barbed upward Coreopsis 
Aigrette of 2 or more scales, or teeth barbed downward Bidens 
TRIBE 6, Helenieae 
Similar to Tribe 5, but receptacle is not chaffy Helenium 
TRIBE 7, Anthemideae 
The scales of the involucre more or less dry, membraneous. 
Heads with ray flowers which are white, or without ray flowers. 
Leaves alternate. 
Heads with white ray flowers. 
Receptacle chaffy. 
Heads bell-shaped,’ smal 9. a) ea!) sy) Achillea 
Heads half-round, rather large 
Receptacle not chaffy. 
Receptacle flat or nearly so . . . . Chrysanthemum 
Anthemis 
Receptacle conical Matricaria 
Heads without ray flowers. 
Heads in broad diffuse flattened clusters . Tanacetum 
Heads in narrow elongated clusters . Artemisia 
TRIBE 8, Senecioneae 
Heads with or without ray flowers. Bracts of the involucre scarcely 
overlapping. Aigrette of soft bristles. Receptacle naked. Anthers 
without tails. 
Leaves all basal. 
Heads _ solitary Tussilago 
Heads in clusters Petasites 
Leaves opposite. 
Margins of leaves wavy . ese Arnica 
Margins of leaves with prominent is - « . . Erechtites 
Leaves alternate, 
Leaves broad, rounded or kidney-shaped . Mesadenia 
Leaves triangular Sty 5c been Synosma 
Leaves spatula-formed, with or without deep lobes, or egg- 
shaped Senecio 
TRIBE 9, Cynareae 
Flower heads large, showy, but without ray flowers; bracts of invo- 
luere overlapping. Anthers with long appendages both at tip and 
base. lLeaved alternate. Aigrette bristly. 
