268 ESS A YS. 



the allied American type, Gaylussacia) will attract attention. 

 It is interesting to note the rapid falling away of Ericaceae 

 westward in the valley of the Mississippi as the forest thins 

 out. 



3. The wealth of this flora in Compositm is a most obvious 

 feature ; one especially prominent at this season of the year, 

 when the open grounds are becoming golden with Solidago, 

 and the earlier of the autumnal Asters are beginning- to bios- 

 som. The Gompoutce form the largest order of Phaenogamous 

 plants in all temperate floras of the northern hemisphere, are 

 well up to the average in Europe, but are nowhere so numer- 

 ous as in North America, where they form an eighth part of 

 the whole. But the contrast between the Compositce of 

 Europe and Atlantic North America is striking. Europe 

 runs to Thistles, to Inuloidece, to Antlicmidece, and to Cicho- 

 riacece. It has very few Asters, and only two Solidagoes, no 

 Sunflowers, and hardly anything of that tribe. Our Atlantic 

 flora surpasses all the world in Asters and Solidagoes, as also 

 in Sunflowers and their various allies, is rich in Eupatoriaceai, 

 of which Europe has extremely few, and is well supplied with 



Vernoniacece and Helenioidece, of which she has none ; but is 

 scanty in all the groups that predominate in Europe. I may 

 remark that if our larger and most troublesome genera, such 

 as Solidago and Aster, were treated in our systematic works 

 even in the way that Nyman has treated Hieracium in Europe, 

 the species of these two genera (now numbering seventy-eight 

 and one hundred and twenty-four respectively) would be at 

 least doubled. 



4. Perhaps the most interesting contrast between the flora 

 of Europe and that of the eastern border of North America 

 is in the number of generic and even ordinal types here met 

 with which are wholly absent from Europe. Possibly we may 

 distinguish these into two sets of differing history. One will 

 represent a tropical element, more or less transformed, which 

 has probably acquired or been able to hold its position so far 

 north in virtue of our high summer temperature. (In this 

 whole survey the peninsula of Florida is left out of view, re- 

 garding its botany as essentially Bahaman and Cuban, with a 



