Trends in the Development of Geographic Botany Author(s): Hugh M. Raup Source: Annals of the Association of American Geographers, Vol. 32, No. 4 (Dec., 1942), pp. 319-354 Published by: Taylor & Francis, Ltd. on behalf of the Association of American Geographers Stable URL: http://www.jstor.org/stable/2561177 . Accessed: 25/08/2011 14:41 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Taylor & Francis, Ltd. and Association of American Geographers are collaborating with JSTOR to digitize, preserve and extend access to Annals of the Association of American Geographers. http://www.jstor.org ANNALS of the Association of American Geographers Volume XXXII DECEMBER, 1942 No. 4 Trendsin the Developmentof Geographic Botany HUGH M. RAUP CONTENTS Introduction................................................................. 319 Theophrastusto Humboldt:Floristic Plant Geography.......... .............. 320 Humboldtto Darwin ................ ........................... 324 The Effectsof Darwinismupon Plant Geography.............. ................ 327 CurrentTrends in Plant Geography: FloristicPlant Geography........................................... 333 Life Formsin Plant Geography........................................... 334 PhysiologicalPlant Geography........................................... 336 Developmentof Geographyas a Whole ........................................ 341 The Natureof Plant Geography........................................... 344 LiteratureCited . .................................................... 350 INTRODUCTION Plant geographershave devoteda greatdeal of attentionduring the past two or three decades to considerationof the methodologyof their field. Their literatureis copiouslysupplied with both short and longpapers dealing with methods:all the way fromdescriptions of highlyinvolved measure- mentsof plantreactions and statisticalmethods for the studyof plant com- munities,to the long and acrimoniousdebate over "Age and Area." Like- wise there is a large and controversialliterature on ecological concepts. Some ecologistsrecognize plant communitiesas highlyorganized entities, whileothers are doubtfulwhether the communities exist at all. With all this discussionof methodsand concepts,the basic ideas upon whichall of plant 319 320 RAUP-TRENDS IN GEOGRAPHIC BOTANY [Dec., geographyrests have eitherbeen taken for grantedor consideredto have onlyacademic, historical significance. The presentpaper is notconcerned with the detailsof thesemethods and concepts,therefore, so muchas withsome trends in whatmight be termedthe logicalapproach to plantgeography. The ideas involvedare not new in the fieldsfrom which they are drawn,but it is hoped thatthey will gain some significancefrom being arrangedin a patternwhich will take themout of theirseparate fields and holdthem up to lightfor comparison and correlations Plant geography,as we now know it, existsin compartments,though to a lesser extentamong some European studentsthan in America. Perhaps the greatestneed withwhich we have to deal is the correlationand integra- tionof workin thesecompartments, and the finalbreakdown of the barriers thatseparate them. It is the purposeof thispaper to pointout what some of the barriersare and how they arose, on the general principlethat an understandingof themwill go a long way towardtheir elimination. If the paper possessesan "argument,"it is thatgeographic botanists stand in need of a criticalexamination of the premisesfrom which they reason; and it is suggestedthat a revivalof morepurely inductive methods might serve not only to unifyvarying points of view but also to clarifyobjectives for the wholefield. THEOPHRASTUS TO HUMBOLDT: FLORISTIC PLANT GEOGRAPHY The firstplant geographers were the "proto-botanists"who firstlearned how to use plantsfor food and shelter. In additionto knowingthe kinds of plants that were useful,they had to know where theycould be found. Later on, when men learned to cultivateplants, it was necessaryto learn enough about naturalhabitats to constructa fair approximationof these habitats,and to arrangetheir materials so as to bringabout a happycoinci- denceof plant,soil and climatethat would producethe desiredresults. The botanyof the Greek naturalphilosophers, such as Theophrastus,was the culminationof untoldgenerations of effortamong primitive men along these lines. Since the botany of the ancient Greeks remainedeffective for a thousandyears and was the startinglevel fromwhich the modernscience "took off,"as it were,during the Renaissance,it will be well to look into it forideas thatcould form the background for our conceptsof plant geography. Theophrastuswas, above all, a practicalgardener; but his knowledgeof the Greekcountryside as well as informationand materialsbrought to him by contemporarytravellers and conquerorsin southernAsia suppliedhim withan abundanceof problemsconcerned with the generaldistribution of vegetation. His writingsare filledwith observations that show a keen and vitalinterest in thegeographic distribution of plants and theirlocal selection 1942] THEOPHRASTUS 321 of habitats. His classificationof theplants he knewwas based in part upon form(trees, shrubs, undershrubs, and herbs), and in part upon positionor habitat selection (Greene, 1909). His gardeningexperience made him consciousof geographiczones of hardinessin the regionhe knew. He re- turnsto thistheme repeatedly, usually correlating the observedphenomena withclimate; and in one place (1: 115), we findthe flatstatement ". that the localityis more importantthan cultivationand tendence." He recog- nized plantsthat preferred shade and othersthat lived mostlyin brightsun. Likewisehe wroteof differencesin the kindsand habitsof plantsthat grew on thenorth and southslopes of hills,and he realizedthe significanceof the mountainsas producersof more differentkinds of plantsand habitatsthan theplains. He knewthe difference between wind and frostdamage to plants. In spiteof his preoccupationwith cultivated things, in one place he devotes no less than eightchapters to the descriptionof naturalaquatic vegetation whichhe dividesinto communities on a physiographicbasis. He wondered about range discontinuities,and the absence of plants fromcertain places, notingthat the cypress was peculiarto Mt. Ida in Crete,and theSyrian cedar to thehills of Cilicia and Syria. He speaks of competitionfor nourishment amongtrees in a forest,and discussesthe dispersalof plants by wind and water; and finally,in discussingthe generationof plants,he describeswhat wouldnow be termed"successions" on riverflood plains and on stirredsoils. Theophrastus'sapproach was freshand naive,unencumbered with any- thingresembling geographic dogma or theory. He describedthe phenomena of plantlife as he saw them,and likewisethe phenomenaof plant habitats. Whereverhe could finda simplefactual coincidence between the two he statedit, usually as merelyanother observed fact, but sometimeswith the implicationof cause and effectrelations. His knowledgewas empirical,and in spiteof the prevailingdeductive logic of his timehis conclusionsseem to have been arrived at by simple inductivereasoning. Furthermore,it is impossibleto separatehis plantgeography from his systematicknowledge of .thekinds of plants. No tangibleadvance was made eitherin the classificationof plantsor in knowledgeof their distribution until the periodof the Herbalistsin the 15th and 16thcenturies. The fortunatecoincidence of eventswhich produced a renaissancein thearts had its influencein botanicalscience as well. Travel and explorationbrought knowledge of plantsfrom many parts of the world, and theinvention of printing and illustrationbegan to diffusethe knowledge. Under theseand otherlike stimuli,men revived a naive interestin theplants thatgrew about them,writing fresh descriptions of themand automatically becoming conscious of differencesamong kinds of plants never before noticed. 322 RAUP-TRENDS IN GEOGRAPHIC BOTANY [Dec., It is unnecessary,in the presentdiscussion, to trace the developmentof systematicbotany from these early beginningsdown to Linnaeus and his successors. But it shouldbe emphasizedthat the geographicbotany of the periodremained inseparable from it. The discoveryof the New World,and such botanicaltravels as that of Tournefortto the Near East (1717), to- getherwith the inventionof a usable systemof botanicalnomenclature and diagnosticdescription (Linnaeus, 1753), gave to studentsa vast amountof new empiricalknowledge with which to thinknew thoughtsabout distribu- tion. Naturally,the firstones to do thiswere the systematicbotanists who had the requisiteknowledge; and therefinally appears the rosterof illustri- ous 19th-centuryfloristic plant geographerswhich begins, perhaps, with Willdenow (1792, 1805) and culminateswith Joseph Dalton Hooker, Asa Gray (1859, 1884), and Engler (1879-82). Floristicplant geographyhas dealt primarilywith the distributionover theearth's surface of the kinds, or speciesof plants. The arrangementof its vast body of knowledgerests, first, upon a clear understandingof the kinds of plants. Having delineatedthe kinds, it has aimed to outline