Geographical Distribution of the Cruciferce. 5 



tbe Rocky Mountains, much information no doubt will be obtained 

 regarding plants, and other subjects of natural history, from 

 the able and zealous naturalists composing that scientific party* 

 The Thompson's and Frazer's River countries display as fine a 

 fieVl for the enterprise of scientific and speculative minds as is to 

 be found in North America. 



Following the Dentaria, we have the genus Parrya, a name 

 given by R. Brown to an Arctic plant or two, to commemorate 

 the distinguished officer, who was amongst the foremost of the 

 discoverers in the expeditions which were set on foot during the 

 present century, to ascertain the reality of a North West passage. 

 As it is a northern plant, I may state that in it the pods are 

 broader than in the genera hitherto mentioned, the valves are 

 veiny, the seeds broadly margined, and the funiculi more or less 

 adherent to the septum. On the Arctic coast, to the eastward of 

 Mackenzie River, we have one species, the Parrya arctica of 

 Brown ; and to the westward of the same river, and on the north- 

 west coast, the Parrya, macrocarpa. By the late Sir John 

 Franklin and his companion, now Sir George Back, the P. macro- 

 car pa was brought home on their second voyage to and from 

 the Arctic coast ; but it must have been known before this to the 

 Russians, Linnaeus having described a variety of it under the 

 name, Arabis caide-nudo. 



The two genera with which Torrey closes the Arabidece of North 

 America are the Phenicaulis and Leavenworthia ; but I pass them 

 over, as the former occurs only to the westward of the Rocky 

 Mountains, at the Forks of Lewis and Clark, on the high hills of 

 the "Wallawalla, and the other is confined to the Central and 

 Southern States. 



AVe are introduced to the tribe Sisymbrece in the genus 

 Hesperis, of which there are two of North America. The Hes- 

 peris minima is the same plant as the H. pyymaza of Hooker, 

 and probably does not differ from the Cherianthus Pallasii of 

 Pursh. It scarcely passes to the southward of the Ai-ctic circle, 

 but stretches from Behring's Straits eastward as far as Great Bear's 

 Lake, where it was found by Sir John Richardson. The II. Men- 

 ziesii is recognized as coming only from California. 



The genus Sisymbrium, like that of Arabis, dispenses its 

 species over Arctic as well as Sub-arctic America, and that too in 

 not very unequal order. The Sisymbrium officinale is sup- 

 posed to have been introduced from Europe into Canada and the 



