264 BOTANY. 
tute of fibro-vascular bundles and with minute flowers of 
simple structure, may be contrasted with the Heaths, Com- 
posites, and Madderworts. The highest development, all 
things considered, is undoubtedly reached in the Compos- 
ites: this is indicated by the number and variety of their 
tissues, the high differentiation of the epidermal structures, 
the aggregation of their flowers into heads, and these 
Fie. 143.—Marsh-marigold (Caltha palustris), with showy yellow perianth. 
often into secondary clusters; by the union of the parts 
of the flower; by its inferior ovary with its single ovule; 
its well-developed embryo; as well as by many other 
things which we have not space to explain here. 
536. As to the arrangement of the Dicotyledons, it is 
probable that a natural dispgsition of the orders would 
place the Choripetale below the Gamopetale, the latter ex: 
