OF ARTS AND SCIENCES. 77 



12 identical with European species.* 



6 nearly identical with European species. 



6 very analogous to European species. 

 15 very distinct species, but of European types. 



9 species almost peculiar to America. 

 10 species quite peculiar to America. 



If now, on the other hand, we examine the Scandinavian species and 

 types, to ascertain which of them are wanting in America, we find the 

 following, viz. : — 



1st. 8 species more or less cultivated throughout Europe, and prob- 

 ably of a more southern oi'igin : 5. undulata, (Jiippophijeifolia,) rubra, 

 (moUissima,) lanceolata, Smithiana, (stipularis,) (Jwlosericea). Four 

 of these (in parentheses) are regarded as hybrids by some botanists. 



2d. Only one species indigenous to Scandinavia, where, as in Swit- 

 zerland, it forms such a multitude of varieties that Schleicher has 

 founded nearly a hundred species upon this one, — viz. S*. nigricans, 

 a truly European species ; of which S. canescens, S. versifolia, and 

 S. amhlgua are by many botanists thought to be hybrid forms. 



To these may be added from the rest of Europe : <S. Silesiaca, 

 ^almost peculiar to Silesia ; S. glabra, of the Austrian Alps ; S. grandi- 

 folia and S. Seringiana, of Switzerland ; S. riparia, S ccesia, and S. 

 pedicellata, in Italy and Spain. 



It appears, therefore, that of the 58 North American species, 24 

 are identical with European ones ; 24 belong to the same types ; and 

 only 10, western or arctic forms, seem to be peculiar to this great con- 

 tinent: and further, that of the Scandinavian tiora only a single in- 

 digenous species or type is not yet found in America (a type which 

 appears as if composed of almost every other) ; while 48 more or less 

 related species or types are common to the New and the Old "World, 

 but more luxuriant and varying in America, where we also find a num- 

 ber of other types. All this leads us to look to America as the chief 

 abode, perhaps the original home, of the Willows, and the country 

 where the gehus ought to be especially studied. Therefore we may 

 call upon American botanists to apply themselves to the investigation 

 of this genus and its intricate forms, as they have already done to 

 another vast genus ( Oarex) which presents an analogous distribution. 



* Half of these were imported from the Old World, and are cultivated or natu- 

 ralized, as already stated on p. 75. A. G. 



