812 ARBORETUM AND FRUTICETUM. PART ITI. 
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 Willughbié//a, and M. centuncularis 
( fig. 548. )are the kinds that most frequently 
attack rose trees. 

Genus XII. 
| 
de 
LO‘WEA Lindl. Tue Lowea. Lin. Syst. Icosandria Polygynia. 
Identification. Lindl. Bot. Reg., t. 1261. 
Synonyme. Rdsa sp. Pall. and Lind/. in Ros. pete 
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 Bot. Reg., t. 1261.) 
Generic Character, &c. The genus Lowea has been separated from that of Rosa 
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 Linnzan 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. 
“ Tt is well known,” Dr. Lindley observes, “ that, since the days of Linnzus, 
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 Negéindo 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 stipule. 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 Bérberis; neither can they be considered as confluent 
stipulz, for the venation is not what would be found under such circum- 
stances, but precisely that of an ordinary leaf.” (Bot. Reg., t. 1261.) 
