l68 GREENE 



terminal origin of its inflorescence, the firmness and compactness 

 of that inflorescence, concurring with small red velvety or plushy 

 drupelets for fruits. 



Of the genus, in this which seems to me the most reasonable 

 and natural acceptation of it, there exist in North America, ac- 

 cording to classic standards, four species, — Rhus glabra, 

 typhina, ptimila and copallina} 



To the last of these there is attributed a geographic range 

 somewhat incredible for that of any one species of shrub of what- 

 ever genus ; almost incredible, I say, to any experienced student 

 of climatology as affecting plant life and the distribution of spe- 

 cies. But according to the books Rhus copallina occurs as one 

 and specifically the same in several widely sundered and very 

 different floral regions. It is said to be common in the hard soil 

 and severe climate of New England, and as much at home in the 

 subtropic lowlands of Florida, twelve hundred miles southwest- 

 ward ; even running away to the arid cactiferous hills of further 

 Texas that lie westward from Florida another thousand miles ; 

 and yet again, in a region so extremely different from either of 

 these as that of the Great Lakes in Minnesota and Wisconsin, 

 the same Rhus copallina y it is said, recurs. 



An European celebrity more than twenty years ago, without 

 field knowledge of the shrubs, and with no experience in prob- 

 lems of North American phytogeography, but using the imper- 

 fect light of European herbarium material only, made out and 

 named a half dozen varieties and subvarieties of our Rhus copal- 

 Una;" 1 all which work is ignored or suppressed by later Ameri- 

 can compilers of books ; to whom the following out of the vivid 

 suggestions of Engler would entail the expenditure of much time 

 and energy, whereas suppression is of all things the most easily 

 done. 



Rhus copallina is one of many hundreds of North American 

 phytologic problems awaiting investigation and solution. 



Another of our four species, namely Rims pumila, stands in 

 most marked contrast to the preceding in point of geographic 



L Torrey & Gray, Flora of North America i : 217. Gray, Synoptical Flora 1 : 



384- 



2 Engler, in DC. Monographic Phanerogamarum, 4: 3S3. 



