CHAPTER XL 



OVERHEAD WATERING— SURFACE WATERING -SUB-WATERING 

 - CUT OF A CROSS SECTION OF A SUB-WATERING BENCH 

 -RELATIVE COST OF BENCHES AND BEDS- 

 OPINIONS OF THEIR MERITS. 



THE amount of moisture a plant requires for its health and 

 development is in ratio to the area of its leaf surface. 

 Nature never makes a mistake in proportioning organs or 

 in the assignment of their functions. It is the function of roots to 

 absorb water from the earth and for the leaves to exhale it in the 

 form of vapor. Leaf surface is an unfailing indication of the 

 volume of liquid vegetable blood required in a plant's circulation. 

 The spacious leafed banana growing in the humid section of the 

 tropics, and the leafless cacti growing in an arid region, are indices 

 ot the demands of their structure for moisture, and of the capac- 

 ity of their roots to absorb it. 



Some plants demand more water than others. Water is the 

 means by which floats to every part of the plant the dissolved nu- 

 triments to build the skeleton of its structure. An adult sun- 

 flower evaporates a quart of water daily; a large oak, one hundred 

 and fifty gallons, or three barrels. These plants have unobstructed 

 capillary tubes, an arterial and veinous system through which their 

 watery blood flows in volume. It is estimated that twenty-five 

 pounds of water must circulate through the system of a plant to 

 deposit one ounce of dry matter. 



A carnation is neither a sunflower nor an oak. Its circulatory 

 system differs from them. It has no heart to pump the blood 

 through its system, a vis f route and vis tergo, is but indifferently 

 developed, and the volume of fluid in its system is small, being 

 one-half less than in aquatic plants. The structure of a carnation 

 like many other plants is composed of cells. The stems and root 



