CHAPTER XLVI. 



DICOTYLEDONS (Concluded). 



Order Aggregate. 



440. Lesson XX. The composite family (compositae). — In 



all the composites, the flowers are grouped (aggregated) into 

 ' ' heads, "as in the sunflower, where each head is made up of 

 a great many flowers crowded closely together on a widened 

 receptacle. The family is a large one, and is divided into 

 several sections according to the kinds of flowers and the differ- 

 ent ways in which they are combined in the head. In the 

 asters there is one common type illustrated in fig. 238 by the 

 Aster novce-anglicB. In the aster, as is well shown in the 

 figures, the head is composed of two kinds of flowers, the 

 tubular flowers and the ray flowers. In the tubular flowers the 

 corolla is united to form a slender tube, which is five-notched 

 at the end, representing the five petals. In the ray flowers the 

 corolla is extended on one side into a strap-shaped expansion. 

 Together these strap-shaped corollas form the "rays" of the 

 head. The corolla is split down on one side, which permits 

 the end then to expand and form the ' ' strap. ' ' This is a 

 ligula, or more correctly speaking a false ligula. In fact the 

 ray flower is bilabiate. By counting the " teeth " of the false 

 ligula there are found only three, which indicates that the strap 

 here is made up of only three parts of the 5-merous corolla. 

 The two other limbs of the corolla are rudimentary, or sup- 

 pressed, on the opposite side of the tube. True ligulate flowers 

 are found in the chicory, dandelion, or in the hieracium, where 

 the five points are present on the end of the ligula. 



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