382 BOTANICAL GAZETTE [june 
ae 
floristically and for 
So different are certain portions of the plains with respect to 
vegetative covering that they may be regarded as scarcely more 
than topographically similar. If North America were to be 
considered alone, a primary division of the vegetative covering 
into forest and plain would be useful in certain respects. But 
these areas are merely the North American representatives of 
certain zones or realms among those into which the vegetation 
of the entire earth is divided. In consequence they are not to 
be distinguished as phytogeographical divisions at all, but as 
aggregates of divisions, which are characterized by a common 
type of vegetation-form, or by a group of such types. 
Grisebach, having in mind apparently only the gross features 
of the continental floral covering, distinguished but four divi- 
sions, forest domain, prairie domain, Californian littoral domain, 
and Mexican domain. In the prairie domain he includes not 
only the prairies proper and the great plains, but the great 
basin, and the high plateaux of Arizona and New Mexico as 
well, styling them eastern, northern, and southern prairies 
respectively. Grisebach practically disregards the true, or east- 
ern prairies, characterizing only the northern and southern ones, 
which are by no means prairies in a phytogeographical sense, 
and scarcely more in a physiographical one. Asa result at OFF 
careful analytical study of the floristic features of the coutiner 
Engler has separated the floral covering into seven provinces: 
(1) North American lake province, (2) Appalachian province, 
(3) Prairie province, (4) Californian coast province, (5) Oregon 
province, (6) Rocky mountain province, (7) Colorado peat 
the last comprising the vast unforested region between the 
Rocky mountains and the Sierra Nevada. - In 1887, in the Adas 
der Phlanzenverbreitung, disregarding division into a. 
Drude outlines a number of vegetation regions upon a hoe 
map of North America, which correspond to the regions 2s 
posed in his Handbuch der Pflanzengeographie. These gt ae 
teen in number: (1) Glacial forest and thicket region of A sie 
(2) Canadian forest region, (3) forest region he aad 
lly distinct from the northern forests. 
