58 CLASS XVIII. ORDER. IV. 



eeptacle naked : egret pilose or plumose. (Florets of- 

 ten all perfect.) 



Artemisia. Calyx imbricate, with scales rounded, 

 converging : egret : receptacle somewhat villose or na- 

 kedish (Flowers mostly round-headed.) 

 B. Flowers radiate. 



Chrysanthemum. Calyx hemispherical, imbricate, with 

 the scales membranous at the margin : receptacle naked ; 

 egret none, or a narrow margin. 



Inula. Calyx imbricate or squarrose : egret simple : 

 .anthers ending in 2 bristles at tiie base : receptacle na- 

 ked : ray florets numerous. 



Erigeron. Calyx imbricate : egret pilose : receptacle 

 naked : florets of the ray linear, very narrow, numerous. 



Solidago. Calyx-scales imbricate, closed : egret sim- 

 ple : receptacle naked, furrowed with dots or punctures : 

 ray -florets about 5, always fewer than 10, ^-toothed. 



Senecio. Calyx cyliridric ; leaiets with withering, 

 blackish tips, and a few small calycle leafets at the base : 

 egret simple : receptacle naked. 



Jlstsr. Calyx imbricate, the inferior scales spreading ; 

 egret simple : receptacle naked, scrobiculate. (Florets 

 of the ray more than 10, except in soHdaginoides, and a 

 few other species.) 



JJnthcmis. Calyx hemispherical, nearly equal : egret 

 0, or a membraneous margin : florets of the ray more 

 than 5 : receptacle chaffy, the chaffs flat, with a rigid 

 acuminate apex. 



ORDER III. POLYGAMIA FRUSTRANEA. 



Rudbeckia. Calyx with a double order of scales : re- 

 eeptacle chaffy, conic : egret a 4-toothed margin or 0. 



Helianthus. Calyx imbricate, sub-squarrose, leafy : 

 receptacle flat, chaffy, egret 2-Ieaved, caducous. 



Centaurea. Calyx various, mostly imbricate, roundish : 

 egret simple, various: receptacle bristly: corols of the 

 ray funnel-shape, longer, irregular. 



ORDER IV. POLYGAMIA NECESSARIA. 



Calendula. Calyx many -leaved, equal : receptacle na- 

 ked : egret none : seeds of the disk mem bran aceous. 



Iva. Calyx 3-leaved : styles 2, long : seed naked, ob- 

 tuse : receptacle hairy : ray 5-flowered. 



