Statistics of the Flora of the Northern States. 381 
- That is, in the first list, or in the species of widest range, 864 
per cent ; ‘in the second, Y 02 per cent; in the third, 76 per cent, 
_ or in all three together 75 per cent of the species belong to 
genera of above the average size. 
The converse does not tell in the same way, so far as our list 
Species of the Northern United States which have some other and 
widely sundered habitation. 
The plants which I here have in view belong to DeGandolle’s 
egory of Disjoined Species (Espéces Disjointes),* or those of 
which the individuals exist in two or more separated countries, 
and which cannot reasonably be regarded as having been con- 
veyed from one to the other by any existing means of transport, 
whether on account of their mode of life, the character of their 
seeds, the extreme distance of their habitations, or any other 
indigenous pheno anous plants common to this country and to 
the Old World are disjoined species. I exclude both those spe- 
The following are the principal cases of the kind with which 
We have to do. 
us minimus. Florida and Georgia to Ilinois, and west 
to Oregon and California. Europe, north to rt oc is 
remarkable that along with the common Mousetail in regon 
gtows the only other species of the genus, M. aristatus, Benth. ; 
* Gé ‘ : 
eographie Botanique, 2, p. 993. : 
Det’. : catalogue of 117 Phenogamous 
8pecies bi andoll (Btogr. econ = ee © is actetaliextion or sori over at 
