8 Mr. Woops on the Genera of European Grasses. 
from a general sense of comparative similarity, no two botanists would per- 
haps exactly agree. Thus Arrhenatherum, placed by Linnæus among the 
Avene, and declared by Sir J. E. Smith to be an Avena in habit, is transferred 
by many botanists to Holcus. De Candolle, or at least Duby, in a work to 
which De Candolle's approbation is attached, and to which his name is added, 
solves the difficulty by putting Holcus and Avena into one genus. But ac- 
cording to Kunth, Holcus does not belong to the Avenacee but to the Phala- 
rideæ ; and as the barren flower of Arrhenatherum is the lowest, this genus 
would belong technically to the second section of Brown, while both Holcus 
and Avena belong to the first; and Kunth, though he places Ho/cus with the 
Phalaridee, yet fixes Arrhenatherum, in spite of its outer barren floret, among 
the Avenaceæ. In these indeterminate problems, if I may use the expression, 
no individual can be very confident that he is in the right, but the question 
in each particular case will at last be determined by the adherence of the men 
of the clearest and most comprehensive views, and who have most carefully 
studied the subject. At present, in the grouping of Grasses, we seem to stand 
but on the threshold ; and while one distinguished botanist invites us in one 
direction and another in another, the bewildered student is at a loss which to 
pursue. 
Reichenbach, though he has distributed his Grasses into tribes, has pro- 
bably given his attention more to the determination of species than to the 
arrangement of genera. His groups are nearly the same as those of Kunth, 
and the variations which he has introduced are not for the better. 
I mention Kunth last, as it is his grouping which I propose nearly to adopt 
as to the natural arrangement of the genera; and I begin with this part of the 
subject, because it is the careful consideration of natural affinities which must 
guide us in the choice of the characters on which each genus is to be esta- 
blished. 
This author, in the work to which I have already referred, divides the 
Grasses into 13 tribes, which, however, he hardly attempts to characterize. 
He gives no explanation of the motives which induced him to put plants into 
the same tribe, or to separate them into different ones ; nor is it easy to ex- 
tract such motives from the short and loose description which he has prefixed 
to each tribe, and which, short and imperfect as it is, is generally contradicted 
