148 BRITISH PLANTS 



staple food of the people living on the dry plains of India 

 and China ; African millet (Dhurra, Guinea or Kaffir corn) 

 is Sorghum vulgar e. Maize (Zea Mais) contains more 

 sugar and oil than most cereals ; it is the only cereal 

 which we owe to America ; in South Africa it is called 

 " mealies." 



Wheat is the most valuable of all the cereals, and the 

 general demand for it among the more prosperous of 

 mankind is increasing every year. Besides starch, flour 

 contains protein and a small quantity of oil. If flour is 

 kneaded with water, the starch can be separated and 

 pressed out through muslin, and the stringy, sticky mass 

 left behind is gluten, which consists largely of protein. 

 A large part of the protein in wheat is contained in a 

 special layer of cells lying close to the surface of the grain. 

 In the best white flour this is removed with the outside 

 husk, with the result that the flour is deprived of a large 

 part of its nourishing qualities. 



Oily Seeds are of more importance to man as a source 

 of oil, extracted for economic purposes, than as food 

 e.g., cotton-seed-oil, coconut-oil, palm-oil for soap-making, 

 castor-oil, coco-butter, linseed-oil from flax-seed, rape and 

 colza-oil from rape-seed. 



The seeds of Sinapis yield mustard, and from the seeds 

 of Strychnos Nux-vomica, strychnin, a deadly poison, is 

 obtained. 



2. Fruits. : Fruits in which any considerable quantity 

 of food-stuff is stored are fleshy. These fruits are par- 

 ticularly adapted to attract the attention of birds and 

 provide them with food, but the seeds are preserved from 

 destruction either by being hard and indigestible, or by 

 being enclosed in hard shells (p. 136). The formation of 

 large fleshy fruits seems at first sight a very extravagant 

 means of providing for the dispersal of the seed, but the 

 method is an extremely efficient one, for there are few 

 other means by which seeds can be carried so far or 

 distributed over so wide an area as by birds. 



Cultivated Fruits. Many succulent fruits have been 

 cultivated by man from very early times, and in the 

 Tropics some, like the banana, form his staple diet. 

 Other examples are apples, pears, plums, cherries, apricots, 

 peaches, gooseberries, blackberries, raspberries, red and 

 white currants, grapes, strawberries, oranges, lemons, figs, 



