a. Growth and assumption of position by 
parts. 
Diurnal movement leaves. 
b. Movements. 
Nocturnal movement leaves. 
Epinasty and hyponasty. 
Nutation of stems. 
g. Active factor in plants. 
10. Responsive factor in plants. 
XI. ECOLOGICAL VEGETATION TYPES. 
Meaning of vegetation type. Contrast with flora. 
Responsive type of vegetation. 
W arming’s classification. 
1. Mesophyte* societies, conditions of environment me- 
dium, Ex., North Temperature regions, except 
mountain heights, arid regions, sand dune areas, 
water, etc. 
2. Xerophyte? societies, condition of environment severe. 
Air, or soil, or both very dry. 
Root absorption difficult. 
Loss of water rapid. 
Ex., of xerophytic situations, 
1. Deserts, sand or gravel hills, rocky places, 
steppes and some prairies. 
2. Soils or waters with large quantities of acids 
or salts. 
3. Hydrophyteé societies. 
Plants in water or in wet situations, or where air 
is very humid. 
Water hydrophytes ; aquatic. 
Land hydrophytes: semiaquatic. 
Hee Italo nytes societies. 
Salt marsh plants. 
Salt basin plants. 
*Mesophyte. wméoos (middle), du7dv (plant) 
{Xerophyte. {mpos (dry,) putdy 
tHydrophyte. bdwp (water), purdv 
@Halophyte. dos (salts), puTdy 
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