HSe ARBORETUM AND FRUTICETUM. PART III. 



(lorn happens before the beginning of summer. On the other hand, very many 

 sorts, in intermediate localities, are intermediate also in their time of flowering. 

 Hence, the same kind, when it inhabits three different regions, cannot be 

 compared together in the same stage of growth in a living state ; and, conse- 

 quently, three species may, in this way, be made out of one. Dr. Host farther 

 observes, that a great impediment to the determining of what are really species, 

 arises from the sexes of a species often inhabiting localities very distant from 

 each other, and sometimes even different regions; and the beautiful figures which 

 illustrate this author's work, on the supposition that they are faithful portraits, 

 clearly show that the male and female differ very considerably in their foliage 

 and wood, independently altogether of their catkins. 



The great master in the genus iValix may be considered Professor Koch, 

 who has done more to advance a knowledge of this genus in his 12mo pam- 

 phlet of 60 pages, De Saliribus Europa'is Cotimcutafio, published in 1828, 

 than the most voluminous of ancient or modern authors. The preface to this 

 pamphlet is so full of instruction as to the mode of studying this family of 

 plants, that we are confident that our readers will feel obliged to us for pre- 

 senting to them the following 



Abstract of Koc/i's Preface to his Commentary ou the Gentis Sa/i.r. The author, 

 after noticing the difficulties to be encountered in this genus, and referring to 

 what has been done by Linnaeus, Wahlenbcrg, Willdenow, Smith, and others, 

 notices the 119 species which had been sent to him by Schleicher, as found 

 l)y that botanist in Switzerland, and thus, as we have before observed (p. \i56.), 

 making the total number of species of ^alix 2.^4. Of Schleicher's species, he 

 says that he could not find one that truly deserved the name.. They are, he 

 adds, mere variations of species long since known ; and, for the most part, dif- 

 ferent forms of one changeable species, viz., his own S. ;;hylicifolia. All 

 Schleicher's kinds are enumerated as species in Steudel's Xomcnclafor ; but 

 Koch treats them as spurious, he recognising not more than 50 truly distinct 

 European species. 



The manner in which Koch obtained his knowledge of the genus 5alix is 

 thus given: — " For a number of years, I observed the willows growing wild 

 in the Palatinate; also those I met with during my travels; and those which I 

 have found, during the space of four years, in the neighbourhood of Erlangen. 

 All the species, or singular forms, which I founil gro\\irg wild were trans- 

 ferred to the garden ; and to these were added kinds sent by my friends 

 Mertens and Zeiher, an addition of no small importance. From the former I 

 received genuine English willows in a living state. The whole cilleclion was after- 

 wards transferred to the Botanic Garden at Erlangen, where, neither care nor 

 expense being spared, it has since been much increased. From M. Otto 

 director of the Botanic Garden at Berlin, I also received a number of kinds. 

 Of dried specimens I have received the whole collection of M. Seringe, from 

 that author himself; and the greater number of the Swedish, French, and 

 English willows, gathered in their native habitats, from Mertens ; forming in 

 the whole a greater number of s[)ecies of this genus than was ever before 

 available by one individual. 



" Every genus of plants has certain peculiar features, with which constant 

 observation and repeated examination alone can familiarise us ; i)ut there is 

 no genus in which it is so necessary as in that of iSalix, to investigate, not only 

 its peculiar characters, but also the growth of the plants, both in a wild and a 

 cultivated state. He who endeavours to characterise a species, either from a 

 dried specimen or from a cultivated plant, is always liable to be deceived in 

 its characters. Hence, amongst all the writers on willows from the time of 

 I^innanis, Wahlenberg alone has clearly described them. He travelled through 

 Lapland, Switzerland, the Carpathian Mountains, and Sweden ; examining 

 the kinds of this genus in their native places of growth ; and, following in his 

 footsteps, came Seringe, also a most ddigent investigator. Taking these 

 authors for my guide, although, in some instances, I have been compelled to 

 differ from them, I here offer a synojisis of the European species of willow. 



" In arranging this genus, and distributing its species, if we i>ut near together 



