RESPONSE OF THE PLANT TO ITS SURROUNDINGS 287 
(1) open ground and (2) woodland. Under the first are in- 
cluded: (a) all cultivated grounds — fields, meadows, lawns, 
pastures, and roadsides, with their characteristic shrubs, 
flowers, and grasses; (b) 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? (814.) 
11. Why do trees grown in dry soil have harder wood than the same 
kind grown in wet soil? (123, 318.) 
