KRoses and Apples 55 
inconspicuous flowers, the corolla being entirely absent; 
but it 1s very probable that they have seen better 
days, for they still produce honey. Most of the 
flowers are deficient either in stamens or pistil, one or 
the other being aborted, and this condition of course 
brings about cross-fertilisation through the visits of 
short-lipped insects. 
The two species of Potervwim also lack petals, and 
but for the fact that the flowers are clustered together 
in rounded heads at the top of the tall flower-stalk, 
they would be unnoticeable. As it is, they are liable 
to be passed by most people as plantain flowers. 
Closely examined, there will be found considerable 
difference in the flowers of the two species. The 
Salad Burnet (Poteriwm sanguwisorba) in most cases 
keeps its stamens and pistils apart; the upper flowers 
in a head producing a pistil only, the lower ones 
stamens only, or occasionally with a pistil among 
them. The plant has,so to speak, turned its back 
upon the insects, and laid itself out for cross-fertilisa- 
tion by wind-agency,—hence its long style branches 
at the summit into a perfect brush of stigmas to 
catch the flying pollen-grain; hence, also, its twenty 
or thirty excessively long stamens, that its extravagant 
output of pollen may be caught by the wind and 
swept away. There are only four calyx-lobes instead 
of the usual five, but in spite of this fact there is so 
close a similarity in the top-shaped receptacle-tube of 
Poterium and Agrimonia, that it is reasonable to 
suppose that Poteriwm’s distant ancestor was an 
ancestor of Agrimonia’s also, and that it had yellow 
petals and was insect-fertilised. For this purpose a 
dozen stamens or less sufficed; but the Salad Burnet, 
