458 APPENDIX. No. V. 
can neither adopt the general equinoctial ratio given by Baron Humboldt, 
namely, that of 1:60, nor suppose with him that the minimum of the order is 
within the tropics. For Cyperaceze, like Rubiacese, and indeed several other 
families, is composed of tribes or extensive genera, having very different rela- 
tions to climate. The mass of its equinoctial portion being formed of Cyperus 
and Fimbristylis, genera very sparingly found beyond the torrid zone; while 
that of the frigid and part of the temperate zones consists of the still more 
extensive genus Carex, which hardly exists within the tropics, unless at great 
heights. Hence a few degrees beyond the northern tropic, on the old continent 
at least, the proportion of Cyperacee is evidently diminished, as in Egypt, 
according to M. Delile’s valuable catalogue ;* and the minimum will, I believe, 
be found in the Flora Atlantica of M. Desiontaines and in Dr. Russel’s 
catalogue of the plants of Aleppo.+ It is not certain, however, that the 
smallest American proportion of the order exists in the same latitude. And 
it appears that in the corresponding parallel of the southern hemisphere, at 
the Cape of Good Hope and Port Jackson, the proportion is considerably 
increased by the addition of genera either entirely different from, or there 
more extensive than those of other countries. 
Among the Cyperacez of the Congo herbarium there are fifteen species of 
Cyperus, of which C. Papyrus, appears to be one. The abundance of this 
remarkable species, especially near the mouth of the river, is repeatedly noticed 
in Professor Smith’s journal, but from the single specimen with fructification 
in the collection, its identity with the plant of Egypt and Sicily, though very 
probable, cannot be absolutely determined. I perceive a very slight difference 
in the sheaths of the radii of the common umbel, which in the plant from 
Congo are less angular and less exactly truncated, than in that of Egypt; in 
other respects the two plants seem to agree. I have not seen C. laxiflorus, 
a species discovered in Madagascar by M. du Petit Thouars, and said to 
resemble C. Papyrus except in the vaginz of the partial umbels.{ 
Among the species of Cyperacee in the collection, having the most extensive 
range, are Cyperus articulatus, which is common to America, India; and 
* Flor, Egypt. Illustr. in Descrip. de V Egypte, Hist. Nat. 2, p. 49. 
+ Nat. Hist. of Aleppo, 2d. ed. vol. 2, p. 242. 
+ Encyc. Method. Botan. vol. 7, p. 270. 
