246 Observations on Humboldt's fVorh 



and, secondly, a similar anomaly is observed on comparine^ the 

 European Flora with the Flora of a district in North America,' 

 which has the same climate ; for example, with the Flora of 

 Philadelphia. According to William Bartram's Prodromus 

 Fierce PhiladelphiccB, the proportions are nearly as follow, the 

 cultivated plants being omitted : — Cruciferce 3^, UmhellifercB -^^ 

 CaryophyllecB '■^. Besides, it might be shewn that the geo- 

 graphical longitude occasions a marked difference. Thus the 

 author himself remarks, p. 72, that ^ of the known Piper acccB 

 are found in America. Moreover it is evident, from the im- 

 mense number of species of Erica which grow at the Cape of 

 Good Hope, that the family to which this genus belongs stands 

 in quite different relations to other phanerogamous plants in 

 Africa, and under the same latitude in South America and New 

 Holland. The great number of Astragali in Siberia shews the 

 proportion of Leguminosas there, to be different from that of the 

 temperate parts of Europe or North America. In Gmelin's- 

 Flora Sibiricaj the Leguminosss make ^V? i^ Germany about 

 ^\^*, The striking difference between a littoral and conti- 

 nental climate, which has been particularly noticed by Wah- 

 LENBERGf, is also Very important here. 



Since the polar zone is of so little extent in respect to geo- 

 graphical latitude, we may here, perhaps, establish laws from 

 the Flora Lapponica only. There is also a great sameness of 

 vegetation in the different countries of the north polar zone, 

 which I myself have had an opportunity of knowing from the 

 inspection of a valuable collection of Greenland plants. In the 

 temperate zone, as has already been remarked, the difference 

 is so great, that no calculation can be made from any single 

 Flora without great errors. But this prevails more in the vast 

 extent of the equatorial zone, where the different countries pre- 

 sent the greatest variety ; and even here the author's calcula- 

 tion is founded on a small number of the plants of one part of 

 the world. 



* Through an error in reckoning the author has ,1^. 

 t Magazin der Gesellschaft naturforschender Freunde zu Berlin, 5ter 

 Jahrgang (18U) 3 Stuck. 



