86 
Mr. Brown’s Observations on the 
the corolla of Compositas, one peculiarity actually existing is 
lost*. 
The principal peculiarity, however, consists in the corolla of a 
s 3 r ngenesious plant, when reduced to its smallestnumber of nerves, 
having these nerves alternating with its segments in the tube. 1 
am acquainted with no instance of this order of reduction in the 
nerves of any other monopctalous corolla, but I observe an ap¬ 
parent tendency to it in Portlanclia and Catesbcea. In the tube 
of the corolla of both these genera there are ten nerves, of which 
the five that alternate with the segments are manifestly stronger, 
and seem to furnish the greater part of the vascular system of the 
upper part of the tube and of the segments; the intermediate 
nerves being there somewhat like recurrent branches. 
I shall conclude this subject by observing, that although the ex¬ 
istence of nerves alternating with the segments of a monopetalous 
corolla, dividing below the sinus and uniting their branches at the 
apex of the segment, be rare, this disposition is comparatively fre¬ 
quent in a monophyllous calyx, especially where its aestivation is 
valvular. Labiatae furnish the most striking examples of this 
structure. I am not however acquainted with any instance of a 
calyx having five nerves only, and those alternating with its seg¬ 
ments.. 
The aestivation or condition of the corolla before expansion is 
the subject of m y second remark on Compositae. I have, in the 
* A still stronger objection to M. Cassini’s definition is, that while its application to 
Compositae is only hypothetical, it very nearly corresponds with the actual disposition of 
vessels in certain polypetalous genera. Thus in Pittosporum revolutum , each of the petals 
has three nerves with distinct origins. Of these the two lateral, evidently within the 
margins, less so, however, than in Hymenopappus, are quite simple in the ungues, and 
ramify more or less in the laminae, near the top of which they unite with each other and 
with the middle nerve. 
observations 
