Chapter II 



HISTORY OF THE SCIENCE 



The first definitely expressed ideas on regularities in the distribu- 

 tion of plants, which we may regard as the beginning of historical plant 

 geography as a science, we find in the work of Wh-LDENOw, "Grundriss 

 der Krauterkunde", which first appeared in 1792. In the seventh 

 section of this work, entitled "Geschichte der Pflanzen", we read: — 



" By history of plants is meant the influence of climate on vegetation, the changes which 

 plants have probably undergone as a result of the revohiHons which have taken place on our 

 globe, their distribution over the earth's surface, their migrations, and, lastly, the provisions 

 nature has made for their preservation" (p. 418).* 



The character of the present distribution of plants caused these 

 questions to arise in Willdenow's mind: Did not the seas occupy more 

 space in former times than now? Was not the globe entirely covered 

 with water, from which projected only the mountain peaks, which in 

 those times were the only habitat of plants? As the seas dried up and 

 the area of dry land increased, the plants began gradually to disperse 

 from these initial habitats. Later hurricanes, earthquakes, and vol- 

 canoes again destroyed plant life over large areas. This is evidenced 

 by plants whose distribution is restricted to small, widely separated 

 localities. "Lands now separated by oceans may, in former epochs, 

 have been united . . . Thus, the northern part of America may 

 have been connected with Europe, New Netherlands ** with the foot- 

 hills of the Cape of Good Hope". 



In addition to these purely historical causes, Willdenow points out 

 a number of extant factors affecting the distribution of plants. Among 

 such factors he mentions the various adaptations for the dispersal of 

 fruits and seeds by the aid of animals, wind, river, and sea currents, 

 and the scattering of seeds by dehiscent fruits. A no less important 

 factor in the distribution of plants is man. He also points out the 

 similarity between aquatic plants and plants growing on mountain 

 peaks, and in conclusion he discusses the origin of various floras. 

 Hence, in this brief treatise we already find elements of modern his- 

 torical plant geography. 



The next work in order of time, which is clearly concerned not with 

 the geography of plants in general but precisely with problems of his- 

 torical geography, is that of Stromeyer, entitled "Commentatio 

 inauguralis sistens historiae vegetabilium geographicae specimen". 

 In this work a clear distinction is made between general plant geog- 

 raphy, "vegetabilium geographia" (phytogeography), and historical 

 plant geography, "historia vegetabiUum geographica " , of which he 

 makes a further subdivision, "historia vegetabiUum geographica appli- 



* Cited from the second edition, Vienna, 1798; italics ours. 

 •* Formerly used to designate Australia. 



10 



