.32 LAWSON OCCURRENCE OF HEATHER IN CAPE BRETON. 



confined to the North,)* and eastward to the Ural Mountains. 

 That is its eastern limit, for it is not known in Siberia, has been 

 , only erroneously reported from the interior of Northern Asia, and 

 is not found in North West America. Humboldt,! after detailing 

 the distribution of heaths and the relations of the North and 

 South African species to those of Europe, remarks, in reference to 

 Calhma vulgaris: 



" This accurate knowledge which we now possess of the mean tempera- 

 ture of several parts of Northern Asia, as well as of the distribution of the 

 annual temperature into the different seasons of the yeal', affords no sort of 

 explanation of the cessation of heather to the east of the Ural Mountains. 

 Joseph Hooker, in a note to his Flora Antarctica, has treated and contrasted 

 with great sagacity and clearness two very different phenomena which the 

 distribution of plants presents to us : on the one hand, ' uniformity of sur- 

 face accompanied by a similarity of vegetation ; ' and on the other hand, 

 * instances of a sudden change in the vegetation unaccompanied by any diver- 

 sity of geological or other features.' * * * * jvfo less striking is the 

 absence of Calhma vxdgaris, and of all the species of Erica throughout all 

 parts of the Continent of America, while the Calluna is found in the Azores 

 and in Iceland. It has not hitherto been seen in Greenland, but was dis- 

 covered a few years ago in Newfoundland." 



According to Professor Asa Gray, the earliest published an- 

 nouncement of Calhma vulgaris as an American plant, is that by 

 Sir William Hooker, in the Index to his Flora Boreali- Americana 

 (vol. ii. p. 280), issued in 1840, where it is stated that : '•' This 

 should have beeii inserted at page 39, as an inhabitant of New- 

 foundland, on the authority of De la Pylaie." Accordingly, in the 

 seventh volume of De Candolle's Prodromus, to the European ha- 

 bitat is added, " Etiam in Islandia et in Terra Nova Americae 

 Borealis." But Dr. Joseph Hooker, in his valuable paper on the 

 Distribution of Arctic Plants,+ observes, " Calhma vulgaris, L. is 

 mentioned in De Candolle's ' Prodromus,' on the authority of a 

 specimeii gathered by La Pylaie, as a native of NcAvfoundland ; but 

 I find no confirmation of this habitat, nor is it found in any part 

 of the American Continent." 



Mr. Bentham had never seen an American specimen, and, re- 

 marks Prof. Gray, " he also overlooked the fact (to which Dr. 

 Seemann has recently called attention) that Gisecke, in Brewster's 



* I have specimens from Italy. 



t Aspects of Nature. Sabine's Translation. Vol. ii. pp- 1-14-14:7. 



X Linn. Trans, vol. 23. 



