138 APPENDIX. 



OUTLINES OF THE GEOGRAPHY AND THE PEOMINENT FEATUEES 

 OF THE FLORA OF MEXICO AND CENTRAL AMERICA. 



Under this head it is proposed to give, approximately, the extent and some of the 

 physical conditions of the various areas into which, for convenience, the country has 

 been subdivided in the paragraphs of the Enumeration dealing with the distribution 

 of each species, together with notes on the aspects and composition of the vegetation, 

 extracted from the most trustworthy authorities ; but no attempt will be made to deal 

 with meteorological phenomena beyond the barest generalizations. It may be explained 

 here that with the intention constantly in mind, from the commencement of this work, 

 to collect all definite information concerning the extent of virgin vegetation, the predo- 

 minence of certain genera and species, and such other particulars as would enable one 

 to form something approaching an accurate idea of the physiognomies of the floras of 

 the different latitudinal and altitudinal regions under consideration, the result is far 

 less satisfactory than could have been anticipated. Indeed, so few facts bearing upon 

 the subject exist in collectors' notes on their plants that it has been thought better to 

 quote from the writings of botanical travellers rather than attempt general descriptions 

 or a re-casting of the materials, based upon the available data, especially as this has 

 already been done by Grisebach, Engler, and other authors, who have followed 

 Humboldt. Furthermore, the only boundaries possible in subdividing the whole 

 country are political ones, in consequence of the plants of many collectors not being 

 more particularly localized. In spite of these disadvantages, it will be apparent, we 

 think, that by grouping some of the southern political areas, and dividing the northern 

 one into two, fairly natural limits are obtained, affording data for sound deductions 

 respecting the diverse elements of the flora. 



The whole area of land whose vegetation is here dealt with is probably less than 

 1,000,000 square miles, and lies between 80° and 115° west longitude (the southern 

 part being very narrow, the northern stretching through about eighteen degrees), and 

 9° and 33° north latitude on the western side, and 26° on the eastern side. An 

 immense coast-line, and a great elevation of the larger part of the country, subjected 

 to widely different climatal influences on the eastern and western sides, are the two 

 prominent features of the country. The southern boundary is practically the railway 

 from Colon to Panama, though a few plants from Portobello and Las Cruces are 

 included ; and the Rio Grande to El Paso, and thence across to the Gila and the head 

 of the Gulf of California, the northern boundary. Lower California, however, is not 

 included. Proceeding from north to south, the order followed throughout this work, 

 there are nominally seven districts or divisions, namely : North Mexico, South Mexico, 

 Guatemala, Salvador and Honduras, Nicaragua, Costa Rica, and Panama ; but, as more 

 fully explained elsewhere, there are only three distinct floral provinces within our limits. 



