RESPONSE OF THE PLANT TO ITS SURROUNDINGS 287 



(1) open ground and (2) woodland. Unde the first are in- 

 cluded : (a) all cultivated grounds fields, meadows, lawns, 

 pastures, and roadsides, with their characteristic shrubs, 

 flowers, and grasses ; (6) heaths and plains of northern or 

 alpine regions, with their low, stunted perennials and bright, 

 but fugacious, flowers. Under the second are classed all 

 woods, thickets, and copses, with the shrubs and herbs that 

 form their undergrowth. These may be grouped in three 

 main divisions : (c) mixed forests of maple, ash, oak, hickory, 

 birch, sweet gum, etc. ; (d) pure forests of pine, balsam, fir, 

 cypress, and the like ; and finally (e) , the perennial splendors 

 of the tropical forest, where the vegetation of the globe 

 reaches its climax in luxuriance and variety of growth. 



Practical Questions 



1. Why do florists cultivate cactus plants in poor soil? (320.) 



2. What would be the effect on such a plant of copious watering and 

 fertilizing ? 



3. Why must an asparagus bed be sprinkled occasionally with salt? 

 (323.) 



4. If a gardener wished to develop or increase a fleshy habit in a plant, 

 to what conditions of soil and moisture would he subject it? (320, 323.) 



5. What difference do you notice between blackberries and dewberries 

 grown by the water and on a dry hillside? 



6. Are there corresponding differences in the root, stem, and leaves of 

 plants growing in the two situations, and if so account for them ? 



7 When a tract of dry land is permanently overflowed by the building 

 of a dam or levee, why does all the original vegetation die, or take on a 

 sickly appearance? (319.) 



8. Should plants with densely hairy leaves be given much water, as 

 a general thing? (202, 320.) 



9. A farmer planted a grove of pecan trees on a high, dry hilltop; 

 had he paid much attention to ecology ? Give a reason for your answer. 



10. Why do the branches of trees often die, or fail to develop, on the 

 windward side? (314.) 



11. Why do trees grown in dry soil have harder wood than the same 

 kind grown in wet soil? (123, 318.) 



