'MS I'LANT LU'K OF A LAMA MA. 



li. ( "oiiUKict or (•(tilt iiiii >u-- plant t'i>iiiiat ii)ii> ol a miilonn t ypc. coiisi.st- 



//. Of mosses or liclicns. 



'. Of ("("spitosc i,Tass('s (incadows, urassy swales). 

 /'. (.)[' various ln'il)> (prairies, pastures). 



</. Of ^l-e^aiious sulll ilteseent i)laiits ;)i' low inuieisiirwhs. 

 /'. Of <;i'ei«farious lar»,'"er, woody plants hianclied fiom the base 



(thickets). 

 /. Of aft)oreaI ve^jfetatioii (()])eii and diMis(^ hi<ili forest). 

 /. Of paludial plants (riparian swamps, marshes, and hoj^s). 

 /. ()f immersed aquatics, floating free or rooted in the soil. 



Considering these natural groups or plant formations in their bio- 

 logical aspect and investigating the mutual relationship between the 

 {)lant and the place where it lives (habitat), Warming tinds that the 

 properties by which a plant is able to adapt itself to the influence of 

 the various factors to which it is exposed and to hold its own in com- 

 petition with its associates are deeply founded in peculiarities of 

 anatomical structure as well as in the morphological development of 

 its organs and the resulting physiological functions. The presence 

 or absence of a type in any given plant formation tinds its explanation 

 in these peculiar modifications of its organism by which its mode of 

 life is regulated, as w^ell as in the ecological relations existing between 

 its own life and the life of its associates. 



On these principles Warming has proposed a new classification of 

 the plant covering of the globe, recognizing four principal groups 

 of associations based on ecological relations, nanudy: 



(1) Hydrophytic vegetation, forming the associations of plants sur- 

 rounded entirely or partially by water or growing in a constantly 

 water-soaked soil. 



(2) Xerophytic vegetation, forming the associations of plants con- 

 fined to an arid soil and a dry atmosphere. 



(3) llalophytic vegetation, making up plant associations restricted 

 to a saline soil, wet or dr}'. 



(4) Mesophytic vegetation, including the general vegetation prefer- 

 ring a soil and an air of medium humidity. 



Of the various plant associations met with in Alabama, those com- 

 posed chiefly of vascular plants will be more thoroughly discussed 

 under this classification of Warming. 



It is self-evident that there exist many intermediate forms between 

 these groups, and these often render it extremely diflScult to assign a 

 certain plant association to a place in one or other of the above groups 

 or (dasses. 



Within each of these four principal groups the vegetation is com- 

 posed of t3'pical forms of plant life, distinguished as trees, shrubs, 



