THE COMPOSITE HEAD 



135 



ch 



B 



FIG. 144. Head of yarrow 



A, top view (magnified) ; B, lengthwise section (magnified) ; re, receptacle ; i, 

 involucre; r, ray flowers; d, disk flowers; c, corolla; s, stigma; ch, chaff, or 

 bracts of receptacle 



FIG. 145 

 Panicle of oat 



FIG. 146. Compound umbel 

 of carrot 



heads as those of the tansy, the thistle, the cudweed, and the 

 everlasting, there are no ray flowers, and in others, like those of 

 the dandelion and the chicory, all the flowers are ray flowers. 



