318 STATE HOETICULTURAL SOCIETY. 



26. State the facts about the flow of the sap. 



The sap is carried upward in the plant through the cells forming 

 the plant body. These hollow cells are tightly filled with sap by an 

 affinity which they have for moisture. The cells thus exert a pressure 

 on the sap much as an elastic rubber bag or bladder exerts a pressure 

 upon water or air with which it may be filled. Evaporation from the 

 leaves takes out sap from the uppermost cells. The cells below press 

 their sap up to take the place of water that is being evaporated, and 

 thus H continual upward current takes place to supply the evaporation 

 from above. When the leaves evaporate faster than the roots can take 

 up water these cells above lose their water faster than it can be replaced 

 andthe plant wilts. There is an erroneous opinion that sap rises and falls 

 in sugar-maples, during the time that the sap is being obtained in the 

 spring. The facts are that the cells of the tree are charged with sap. 

 In warm days this sap thaws out and the cells exert a pressure on the 

 sap in them. If tapped, the tree will give off sap from the cut tissues. 

 When growth of the sugar tree begins, and evaporation begins through 

 the starting leaves the flow of sap ceases. 



27. What does it mean to callous plants? 



To callous plants is to cut them, tie in bundles and set them in 

 dark cellar, with the cut ends in the sand or dirt. They callous them- 

 selves. 



27. What are some of the conditions required for plant growth 

 and development? 



Heat, light, air, moisture and food. 



29. What principles are true concerning the length, size, etc., of 

 roots as compared with the branches of trees ? 



Roots are longer, but not so large. 



30. What are the principle factors to be considered in apple 

 growing ? 



Climate soil, market and varieties. 



31. Mention some of the well-kept botanical gardens in the world, 

 and give a brief sketch of them. 



Shaw's Botanical Garden at St. Louis, Mo., is devoted to scientific 

 research and training of botanists. 



Government garden at Washington, D. C, for the improvement 

 of native plants and introduction and dissemination of foreign ones. 



The best known is the Royal Botanical Garden and Arboretum at 

 Kew, near London, England. This was established by the mother of 

 George III in 1760. Seventy acres of land are devoted to the garden 

 and 178 to the arbaretum. The cost of maintaining the whole is about 

 $100,000 per year. 



