600 General and Applied Biology 



1 



Regions of Vegetation of North America (See Fig. 312) 



A. Tundras 



a. Deserts 



C. Grasslands 



D. Forests 

 (a) Northern 

 evergreen 



(b) Southern 

 evergreen 



GENERAL CHARACTERISTICS 



Fringes the northern limits of North 

 America from Labrador to Alaska 

 (north of latitude 55 to 60°) 



Long cold winters 



Limited moisture ; light snowfall 



Air dry in winter 



Strong winds 



Short growing season because upper 

 limits of soil thaw slightly and 

 ground water is cold 



Soil temperature low 



Most of Arizona and Nevada; south 



ern parts of New Mexico, Cali 



fornia and Texas 



lower California 



Mexico 

 High evaporation of 



plants due to intense heat and low 



atmospheric moisture 

 Intense and generous sunlight 

 Small amount of rainfall 

 Winds fairly strong 



peninsula of 

 and northern 



moisture from 



Extends from central Texas to Mani- 

 toba and along foothills of the 

 Rocky Mountains from New Mex- 

 ico to Alberta 



Soil rich in humus overlying sand 

 and clay 



Few trees probably because of 

 limited soil moisture and exces- 

 sive evaporation due to excessive 

 heat 



Light annual rainfall 



PLANTS TYPICALLY 

 PRESENT 



Certain mosses 

 Certain lichens 

 Certain grasses 

 Certain sedges 

 Certain herbs 

 Certain low shrubs 

 Certain dwarf willows 



From Atlantic to the Pacific Oceans 

 between the tundra on the north 

 and the Great Lakes on the south; 

 extends northwestward to Alaska 



Sagebrush 



Cacti with small, spine- 

 like leaves to protect 

 and prevent excess 

 evaporation 



Yucca trees 



Certain species of bunch 

 grasses 



Few species of small 

 herbs 



Various species of bunch 



grasses 

 Various types of cacti 

 Various kinds of shrubs 



Southeastern U. S. from Texas to 



Florida and Virginia 

 Many low, rolling sandy plains 

 Many large swamps 

 Also high coastal plains farther from 



the ocean 



Cone-bearing trees as: 



Spruce 



Balsam fir 



White pine, red or 

 Norway pine, jack 

 pine 



Hemlock 



Arbor vitae 

 Deciduous trees as: 



Balsam poplar 



Aspen 



White birch 



Long-leaf pine 

 Short-leaf pine 

 Water oaks 

 Bald cypress 

 Magnolia trees 

 Gum trees 



