2 BEGINNER'S BOOK OF GARDENING 



in themselves a certain reserve of nutriment wherewith 

 to start growth in the succeeding year, before the season 

 has sufficiently advanced for them to gather fresh supplies 

 of food. This is especially noticeable in the case of those 

 plants which flower early in the year. The fleshy 

 creeping stems of primroses, the bulbs of crocuses, tulips, 

 and daffodils, the corms of winter aconites and anemones, 

 all offer evidence of this thriftiness of plants. 



For plants to absorb food a certain degree of heat is 

 essential. No plant can feed when its temperature is as 

 low as the freezing point, and most plants require a very 

 much higher temperature ; nor is any active process 

 possible in the absence of a certain degree of water. 



The leaves of a plant are of the utmost importance to 

 its health and life. The under surface and sometimes 

 also the upper surface of each leaf is furnished with 

 little mouths or stomata, to the number of loo to 

 100,000 per square inch, and through these stomata 

 carbonic acid gas is absorbed from the atmosphere, in 

 the plant the gas being broken up by the activity of the 

 green colouring matter or chlorophyll into its constituent 

 elements, carbon and oxygen. The oxygen is given off* 

 and the carbon is retained to join with other elements 

 derived from the roots to form the compounds of 

 which the plant is built. This action of the leaves is 

 only possible when they are exposed to sunlight. 



The other great function of the leaves is to transpire 

 from their surface watery vapour which originally has 

 been absorbed in the liquid form by the root. 



The importance of these processes will be obvious to 

 everyone. As has been said, all the labour of plants, by 

 which from air, water, and a pinch of divers salts scattered 

 in the soil it builds up leaf, stem and roots, and puts 

 together material for seed or bud or bulb, is wrought and 

 wrought only by the green cells which give greenness to 

 leaf and branch and stem. We may say of the plant that 



