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- 
tte) 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 (¢nvolucre), 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-flowcrs. 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 
