208 



PHYSICAL ENVIRONMENT 



cold. A favorable exposure for any plant is one which 

 supplies the requisite amount of warmth, room, sunlight, 

 moisture, and plant -food, and immunity from severe winds 

 and other destructive agencies. Against the edge of a 

 forest (Fig. 356) or at the base of a cliff, certain plants 

 thrive unusually well. Note the plants of any kind grow- 



356. The flowering dogwood is seen at its best along the margins of the wood. 



ing in different exposures: observe that they vary in 

 stature, time of maturity, color of foliage and flowers, 

 productiveness, size of leaves and flowers, longevity. 



Review. Contrast physical and organic environments. How are 

 p^nts modified by climate? Define acclimatization. Explain bow time 

 of maturity is influenced by climate. How is germination influenced ? 

 Explain bow climate influences stature. How do winds affect plants ? 

 How are plants influenced by soil ? By soil moisture ? Exposure ? 



