292 



D ICO T YI.ED ONS. 



Fig. 397- 



scales. ) The stamens are united by their anthers into a tube 

 (syngenecious) which closely surrounds the style. (In am- 

 brosia the anthers are sometimes distinct. ) The style in pushing 

 through brushes out some of the pollen from the anthers and 

 bears it aloft as in the bell-flower, but the stigmatic surface is 

 not yet mature and expanded, so that close pollination cannot 

 take place. There are usually no stamens in the ray-flowers. 

 The ovary is composed of two carpels, as is 

 shown by the two styles, but there is only one 

 locule, containing an erect, anatropous, ovule. 



The floral formula for the composite family\ 

 then is as follows: Ca5, C05, A5, G2. 



555. The rattlesnake- weed (Hieracium veno- 

 sum) is an example of another type, with only .„. , 



/ ^ J ir ^ J Diagram of composite 



one kind of flower in the head, the true ligu- "o™"- (Vines.) 



late flower. The hawkweed, or devil's 

 paint-brush (H. aurantiacum) is a re- 

 lated species, which is a troublesome 

 weed. The dandelion and prickly 

 lettuce are also members of the ligulate- 

 flowered composites. A number of 

 the composites have only tubular 

 flowers, as in the thoroughwort- (eu- 

 patorium) and everlasting (anten- 

 naria). 



556. The extent to which the union of the 

 parts of the flower has been carried in the 

 composites, and the close aggregation of the 

 flowers in a head, represent the highest stage 

 •of evolution reached by the flowers of the 

 angiosperms. The composites stand just 

 above the bell-flowers and lobelias, at the 

 termination of a series. The teasels show 

 a relationship to the composites in the aggre- 

 gation of the flowers in a head. But the con- 

 solidation of the parts of the flower has not been carried so far, and the 

 flowers are each separated by an "epicalyx " in the form of a minute cup- 

 shaped involucie. The teasels stand at the termination of another series in 



Fig. 398. 

 Rattlesnake-weed (Hieracium ve 



nosum). 



