310 A TEXT-BOOK OF BOTANY 



as well as other alkaloids, and is commonly called Peru- 

 vian bark. It is stripped from the trees by the Indians 

 and carefully dried. Although the trees are becoming 

 more scarce every year, no attempt has been made to 

 cultivate them where they are native; but in Java, British 

 India, Ceylon, Japan, and Jamaica there are extensive plan- 

 tations of cinchona. 



174. Composites. This is the highest family (Compos- 

 ites) of Dicotyledons, and contains the most numerous 

 species. Composites are found everywhere, but are most 

 numerous in temperate regions, where they are usually 

 herbs. 



The name of the family suggests the most conspicuous 

 feature; namely, the organization of the numerous small 

 flowers into a compact head which resembles a single flower, 

 formerly called a compound flower. So common are the 

 Composites that the general structure of the head should 

 be understood. Taking the head of Arnica as a type *(Fig. 

 298, A), the outermost set of organs consists of more or less 

 leaf -like bracts or scales (involucre), which resemble sepals 

 (not seen in figure) ; within these there is a circle of flowers 

 with conspicuous yellow corollas (rays), which are split 

 above the tubular base and flattened into a strap-shaped 

 body (Fig. 298, B), and much resembling petals; within the 

 ray-flowers is the broad expanse called the disk, which is 

 closely packed with very numerous small tubular flowers 

 known as disk-flowers. If a disk-flower be removed, it will 

 be discovered that the ovary is inferior, and that arising 

 from it, around the tubular corolla, there is a tuft of delicate 

 hairs (pappus) which represent the sepals (Fig. 298, C). 

 This pappus surmounting the akene ( 143) in Composites 

 may be lacking; it may be a tuft of hairs, as in Arnica, 

 thistle, and dandelion; it may be a cup or a set of scales; 

 or it may develop grappling appendages, as in Spanish 

 needles (Fig. 257) and beggar-ticks (Fig. 258). Most of the 



