252 ESS A YS. 



dor, to which was added a couple of hundred of species known 

 to him outside these limits northwestward. 



Torrey and Gray's Flora took the initiative in annexing 

 Texas, ten years before its political incorporation into the 

 Union ; although the only plants we then possessed from it 

 were certain portions of Drummond's collections. California 

 was also annexed at the same time, on account of Douglas's 

 collections, and those of Nuttall, who had just returned from 

 his visit to the western coast, which he reached by a tedious 

 journey across the continent over ground in good part new to 

 the botanist. Douglas had already made remarkably full 

 collections along a more northern line. The British arctic 

 explorers, both by sea and land, had well developed the bot- 

 any of the boreal regions, and Sir William Hooker was bring- 

 ing out the results in his Flora of British America. Of 

 course our knowledge of the whole interior and western re- 

 gion was small indeed, compared with the present ; and the 

 botany of a vast region from the western part of Texas to the 

 Californian coast was absolutely unknown, and so remained 

 until after the publication of the Flora was suspended. 



As to the number of species which Torrey and Gray had to 

 deal with, I can only say that a rapid count gives us for the 

 first volume about 2200 Polypetalm ; that there are one hun- 

 dred and nine species in the small orders which in the second 

 volume precede the Compositce ; and that there are of the 

 Composites 1054. So one may fairly conclude that if the 

 work had been pushed on to completion, say in the year 1850, 

 the 3076 species of Pursh's Flora in the year 1814 might have 

 been just about doubled. Probably more rather than less ; for 

 if we reckon from the number of the Compositce, and on the 

 estimate that they constitute one-eighth of the phaenogamous 

 plants of North America, instead of 6150, there would have 

 been 8430 species known in the year specified. 



It most concerns us to know the number of species which, 

 after the lapse of thirty years more — years in which explora- 

 tion has been active, and has left no considerable part of our 

 great area wholly unvisited — the now revived Flora has to 

 deal with. We can make an estimate which cannot be far 



