CHAPTER XII 

 LIFE FORMS AND SYNECOLOGICAL UNITS 



The form which the vegetative body of the plant produces as the 

 result of all the life processes which are affected by the environment 

 has been designated the "vegetative form," "growth form," or "life 

 form." Under the caption of life form are brought together those 

 organisms that in their entirety show similar morphological adjust- 

 ments to the environmental complex. 



As far back as the work of Alexander von Humboldt ("Physiog- 

 nomik der Gewachse," 1806) we find attempts at a grouping of the 

 forms of vegetation. Although the basis of his nomenclature was 

 physiognomy, a few of his plant forms, such as cactus form, banana 

 form, casuarina form, express an ecological adjustment. Building 

 upon Humboldt's ideas, Grisebach (1872) attempted to prove the 

 dependence of plant forms upon climate. His summary of plants 

 under 54 different "forms of vegetation" adhered much too closely to 

 physiognomy, that is, to the leaf form, and became lost in its own 

 complexity. Kerner (1863) divided the manifold forms of plant life 

 into 11 purely morphological "basic forms." He emphatically stated 

 that these basic units must be chosen independently of the systematic 

 position of the plants. Pflanzenphysiogtiomik und Sijstematik gehen 

 ja ganz verschiedene Wege (p. 281). He distinguished: trees, shrubs, 

 undershrubs, mat plants, herbs, hanas, filamentous plants, reeds, 

 grass forms, fungi, and crustose plants. 



More recently Drude attempted to "cull out the ecologically 

 uniform members of the major phylogenetic series of the plant world 

 and to classify them from a morphologic-systematic viewpoint" 

 (1913, p. 23). Warming (1908), hke Kerner, threw aside purely 

 systematic-morphological distinctions for the characterization of life 

 forms. At the same time he was not unmindful of the almost insur- 

 mountable difficulties which stand in the way of any attempt to bring 

 order out of the chaos of individual organic forms. For his classifica- 

 tion he used various characteristics of the plant, such as structure of 

 the shoot, sequence of shoots, bud and root formation, sequence of 

 flowers and leaves, duration of life, overwintering, rejuvenation, and 



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