CHAP. CIII. SALICA‘CEH. SA LIX. 1489 
Plantarum of Linnzus, and the Species Plantarum of Willdenow, have the 
synonymes of other authors added to them. ; 
In our App. iii. to the genus Salix will be found the characters of Koch’s 
10 different groups; and under each the names and synonymes of the species 
which he has assigned to them. 
From the perusal of Koch’s observations, two points, we think, will be ren- 
dered clear to the botanical reader: —1. That the mode of arranging the 
sections according to the character of the leaves, adopted by all the Linnzan 
school previously to the time of Wahlenberg, is altogether defective; and, 
2. That the system of throwing the species into natural groups, as adopted by 
Wahlenberg, Fries, Koch, and Borrer, is the true one. Being ourselves of 
this opinion, the only question that remained for us to decide was, whether 
we should follow Koch or Borrer in the arrangement of the species described 
in this work as in a living state in British gardens. 
The excellence of Koch’s system was strongly impressed on our mind 
from the moment that we saw it developed in Dr. Lindley’s Synopsis of the 
British Flora ; and, if we could have classed all the numerous sorts of willows 
in the salictum at Woburn, and in the Hackney arboretum, under Koch’s ten 
groups, in a manner satisfactory to ourselves, we should have done so; the 
more especially as, from observing with care all the different sorts in the 
Hackney arboretum, at different periods, from March to December, 1836, we 
felt convinced in our own mind that by far the greater number of them were 
varieties, and chiefly of S. caprea L. Not being able to do this, we determined 
on endeavouring to obtain the advice and assistance of the first authority in 
Britain on the subject of willows; and we accordingly applied to Mr. Borrer, who 
_at once, in the most kind and liberal manner, classed the sorts contained in the 
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Salictum Woburnense in the 22 groups into which, with the exception of a few 
sorts, they are thrown in the following article. Mr. Borrer’s knowledge 
of this genus is universally known. He possesses an extensive collection of 
living plants, which he has cultivated for some years; and, as Sir W. J. Hooker 
remarks, “ No one has ever studied the willows, whether in a growing or a 
=e state, <e deeply, or with a less prejudiced mind.” (Brit. Fl., ed. 3., 
vol. i. p. 416. 
The botanical details which we have given of each particular species, in- 
cluding a comparison of specimens obtained in a living state from the arbo- 
retaum at Flitwick, from that at Goldworth, and from the salictum at Messrs. 
Loddiges’s, were made out for us, with great care and industry, by Mr. Denson. 
Our figures were chiefly drawn for us by Mr. Sowerby, from specimens received 
from the salictum at Woburn Abbey; in the single instance of the S. caprea, 
reduced from Host’s work; and nearly all the remainder, including all the 28 
ence of leaves of the natural size, by the kind permission of the Duke of 
edford, have been copied from the Salictum Woburnense. 
It will thus appear that our article, lengthy and elaborate as it is, is, in a 
botanical point of view, chiefly to be considéred as matter for a history of 
willows, rather than as a complete history in itself. Such a history, indeed, 
can only be prepared by a botanist who has hed all the species in a living state 
under his eye for several years; and who has applied to them one general 
principle of contrast or comparison. Till this is done, not only with the genus 
Salix, but with every other genus of which there are numerous species, a 
decided imperfection must ever be found in works like the present, in which 
the specific characters are necessarily made up of descriptions given by dif- 
ferent individuals, at different times, and in different countries ; some from 
living plants collected from their native habitats, others from living plants 
grown in gardens, and many from dried specimens. All this shows the great 
advantage that would result to botany and arboriculture from a national 
arboretum; in which not only all the species and varieties should be col- 
lected, but also both the sexes of all the kinds that have the male and female 
flowers on different plants. Such an arboretum, on a sufficiently large scale, 
_ and properly managed, would form a living standard of reference, both for the 
botanist and the cultivator. 
5E 2 
