jj 2 BOTANICAL GAZETTE. 



The area which Pursh's Flora covered was, we may say, the 

 United States east of the Mississippi, with Canada to Labrador, to 

 which was added a couple of hundred of species known to him out- 

 side 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 ot 

 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 b tanist. 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 botany of the boreal regions, and Sir Wm. Hooker was bring- 

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

 knowledge of the whole interior and western region 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 ol the Flora 

 was suspended. 



As to the number of species which Torrey and (I ray had to 

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

 volume about 2200 Polypetalae; that there are 109 species in the 

 small orders which in the second volume precede the Composite?; 

 and that there are of the Composite 1054. So one may fairly con- 

 clude 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 Composite, and on 

 the estimate that they constitute one-eighth of the plnenogamous 

 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 exploration 

 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 wrong. In the 

 year 1878, my colleague. Mr. Watson, finished and published his 

 Bibliographical Index to the Polypetalse ot North America, cover- 

 ing, that is, the same ground as the first volume of Torrey and 

 and Gray's Flora, completed in 1840. In it the 2200 species. of the 

 latter date are increased to 3038. The " Gamopetala after Com- 

 posites" in the Synoptical Flora, brought out in the same year, 

 contains 1656 species. The two together must make up half ot 

 our phsenogamous botany, that is. adding the increase ol the last 

 four years, about 5000 species. And so lVlr. Watson adopts the 

 estimate of 10,000 species for our known Phamogams and Ferns. 



