812 



ARBORETUM AND FRUTICETUM. 



PART III. 



with a brown, and sometimes rather glaucous, body, and a black head. These 

 caterpillars are, at first, very small, and look like little brown grubs : they 

 generally begin to appear in the latter end 

 of April, or the beginning of May, when 

 the rose-buds on the young shoots are only 

 partially developed. At this season, the 

 bushes should be looked carefully over, and 

 the insects picked off with the hand. If 

 this should be neglected, two or three buds 

 in every cluster will be destroyed, or be- 

 come what is commonly called wormeaten, 

 producing only damaged or abortive flowers. 

 The leaf-cutter bees also frequently attack 

 rose-leaves, out of which they cut circular 

 pieces to serve for lining their cells. Me- 

 gachile Willughba'/Zff, and M. centuncularis 

 {fig. 548. )are the kinds that most frequently 

 attack rose trees. 



Genus XII. 



LO^WEyl Lindl. The Lowea. Lin. Syst. Icosandria Polygynia. 



Idenlification. Lindl Bot. Reg., t. 12G1. 



Synonyme. Rbsa sp. Pall, and Lind/. in Hos. Monoe. 



Derivation. In compliment to the Rev. Mr. Lowe, Travelling Bachelor of the University of Cam- 

 bridge- a gentleman now residing in Madeira, from whose botanical investigations of that island 

 we expect important results. {Lindley in Sol. Reg., t 1261.) 



Generic Character, Sfc. The genus Lowea has been separated from that of i?osa 

 by Dr. Lindley, for the following reasons ; which, independently of their 

 application to this genus, we consider to be extremely interesting and im- 

 portant, in a physiological and systematic point of view. It has always 

 appeared to us, since ever we began to think on the subject, that neither 

 genera nor species ought to be founded upon mere technical differences in 

 any one part of the plant, as the orders and classes are in the Linnaean sys- 

 tem ; but on all the parts of the plant, and on all the circumstances con- 

 nected with it, as the orders and tribes are according to the natural system. 

 " It is well known," Dr. Lindley observes, " that, since the days of Linnaeus, 

 the characters of the genera of flowering plants have been exclusively taken 

 from the organs of fructification ; while those of vegetation have been rigor^ 

 ously excluded. This has arisen from the former having been supposed, in 

 all cases, to be more constant in their modifications, and less subject to 

 variation than the latter. No other reason can be assigned for the value 

 thus exclusively ascribed to the organs of fructification. It is, however, 

 time that botanists should disembarrass themselves of this ancient prejudice ; 

 and that they should admit publicly that by which they are constantly in- 

 fluenced in private; viz. that important modifications of the organs of 

 vegetation are sufficient to divide into genera species which do not essen- 

 tially differ in the organs of fructification. Of this the Indian cypripediums 

 are one instance; the genus Negundo is another; and the subject of 

 this article is a third. The structure of the flower of Lowea is, in every 

 part, that of a rose ; but its foliage is not even that of a rosaceous plant ; 

 there being no trace of stipulae. The simple leaves are not analogous to 

 the terminal pinna of a rose leaf; for there is no trace of the articulation 

 upon the petiole, which is required to indicate a reduction of a compound 

 leaf, as we find in Berberis ; neither can they be considered as confluent 

 stipulae, for the venation is not what would be found under such circum- 

 stances, but precisely that of an ordinary leaf" {Bol. Reg., t. 12G1.) ^ 



/ 



