A REVERSION TO AN ANCESTRAL CONDITION 

 Here are the capitula, or heads, of two different types of Crepis capillaris, a wild plant of the 

 sunflower family. The ripe achenes (small, /flry, one-seeded fruits) have been removed. The normal 

 condition of this plant is shown in the smooth flat-topped receptacle at the right. The head at 

 the left shows a reversion to some distant pre-composite ancestral plant in which each seed had a 

 l)ract at its base. Normal plants possess bracts only around the head. (Fig. 16.) 



TOP VIEW OF THE SAME HEADS SHOWN ABOVE 

 Composites emi)race the most highly developed families in the vegetable kingdom. They are 

 characterized by having many small flowers or florets borne in compact heads resembling single 

 flowers^ — such as the daisy, (landelion, aster, and simflower. The composites form about one- 

 tenth of the living seed plants and arc distributed in all |).irls of the world. The\- are considered 

 the highi'st plants on account of the remarkable extent to which th(\ dis[)l.i\' union of parts. 

 (Fig. 17.) 



