282 TEXTBOOK OF BOTANY 



Sometimes this new combination of qualities is a very valu- 

 able one. The production of hybrids is one of the means 

 used to secure new varieties of plants, and some of the 

 results that have been accomplished in this way will be 

 discussed in Chapter XXIII. 



289. Some Practical Uses of Flowers. Apart from their 

 value for ornamental purposes, the only practical uses to 

 which flowers are put on a large scale are the manufacture 

 of perfumes and drugs. They do not ordinarily contain 

 food substances in large enough quantities to make them 

 useful as articles of diet. The flowers of the cauliflower, 

 however, are an exception to this rule. The head of the 

 cauliflower is a thickened flower cluster which has been 

 much changed during the centuries that it has been culti- 

 vated. We eat the flower buds, the flower-stalks, and the 

 bracts. If the plant is kept alive through the winter and set 

 out again the next spring, it sends up a tall flower-stalk that 

 bears ordinary flowers, and that produces fruits and seeds. 



The artichoke (or " French artichoke," so called to dis- 

 tinguish it from the " Jerusalem artichoke " whose tubers 

 are eaten) is a member of the composite family. We eat 

 the bracts which are attached just below the head of flowers, 

 and the soft, thick end of the flower-bearing branch. The 

 flowers themselves are not eaten. Cloves are the dried un- 

 opened flower buds of a tropical tree. The tree seems to 

 be a native of the Molucca Islands, but it is now cultivated 

 in various tropical countries. The dried buds contain about 

 eighteen per cent of the oil known as oil of cloves. Among 

 the flowers used for medicinal purposes are those of the 

 arnica, calendula, camomile, hemp, saffron, henbane, hore- 

 hound, and peppermint. Pyrethrum or insect powder is 

 made from the dried flowers of certain plants of the com- 

 posite family. 



