HOW FLOWEBS CLUB TOGETHER. 155 



flowers differ from the true composites in two 

 or three particulars. In the first place, each 

 tiny flower has a distinct green calyx, of five 

 sepals; while the composites have none, or at 

 least a degraded one. In the second place, the 

 stamens are free, while in the composites they 

 have united in a ring or cylinder. In the third 

 place, the ovary is divided into from two to five 

 cells, a reminiscence of the original five distinct 

 carpels ; whereas in the composites the ovary is 

 always single and one-seeded. In all these 

 respects, therefore, the composites are later and 

 more advanced types than, say, the sheep's-bit, 

 which is a flower-head composed of very tiny 

 harebells. 



The composites, then, started with florets 

 which had little or no calyx, the sepals having 

 been converted into tiny feathery hairs, used to 

 float the fruit (as in thistledown and dandelion), 

 about which we shall have more to say in a 

 future chapter. They had a corolla of five 

 purple petals, combined into a single tube. 

 Inside this again came five united stamens, and 

 in the midst of all an inferior ovary with a 

 divided stigma. Hundreds of different kinds of 

 composites now existing on the earth retain to 

 this day, in the midst of the greatest external 

 diversity, these essential features, or the greater 

 part of them. 



You may take the thistle as a good example of 

 the composite flowers in an early and relatively 

 simple stage of development (Fig. 36). Here 

 the whole flower-head resembles a single large 

 purple blossom, To increase the resemblance, 



