28 POPULAR FRUIT GROWING. 



in a year, it may liave talten from the soil and given off to 

 the air from 500,000 to 1,500,000 pounds of water or from one- 

 quarter to one-half as much as agricultural crops. It has been es- 

 timated that the leaves of deciduous trees transpire one-sixth to 

 one-third as much water as an equal surface of water. Large 

 deciduous trees undoubtedly give off as much as a barrel of water 

 a day in dry summer weather. Coniferous trees transpire much 

 less water than most deciduous trees, frequently not over one- 

 sixth as much. 



Mineral substances are taken up by plants in small quanti- 

 ties and consist mostly of lime, magnesia, potash and phos- 

 phorus. They are carried to the leaves where they are used, 

 (perhaps also on their passage through the tree), with a part 

 of the water in food preparation. The main part of the mineral 

 substances taken up remains, as the water transpires in the 

 leaves and young twigs, and is returned to the soil when the 

 leaves are shed. 



Rest period of plants. — ^With very few exceptions, all plants 

 require an occasional rest period for their best development. 

 Some species get it naturally by being dried and others by be- 

 ing frozen. Even when plants are kept under growng condi- 

 tions the year round, they have periods of rest and of active 

 growth. During the rest period plants undergo very few 

 changes, and yet there is undoubtedly some growth during 

 mild weather in winter, and as evaporation must be going on 

 most of the time from twigs and buds water must be supplied 

 from the roots. 



Classification of fruits. — The commercial fruits of the 

 world may be grouped under the following heads, of which only 

 the more important Northern grown fruits are referred to here. 

 Class I. Orchard culture or tree fruit culture. 

 Sub-class 



I. Pomaceous fruits: Apple, pear, quince. 

 II. Drupaceous or stone fruits: Plums, peach, cherry. 



III. Citrus fruits: Orange, lemon, lime, etc. 



IV. Moraceous fruits: Mulberry, fig. 

 v. Anonaceous fruits: Pawpaw. 



VI. Myrtaceous fruits: Guava. 



VII. Sapotaceous fruits: Sapodilla. 



VIII. Anacardlaceous fruits: Mango. 



IX. Ebenaceous fruits: Persimmon. 



X. Leguminous fruits: St. Johns bread, tamarind. 



XI. 'Nut fruits: Nuts of various kinds. 



XII. Palmaceous fruits: Cocoanut, date, etc. 



XIII. Miscellaneous tree fruits: Olive, pomegranate. 



