DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 319 



which are longer than their pedicel, not twice as short. Fries retains arctica, Schlecht., 

 as a species not yet sufficiently established. 

 C. Wahleiibergii, Rupr. {Anglica, Wahl., Fl. Lap., non L.). Ruprecht remarks of the 

 Samoied plant that the leaves are almost those of C. Danica,!^., but the siliquse- 

 elliptic, the valves sometimes nerved, and much narrower than in true Anglica. 



Hesperis Fcdlasii, Torr. & Gray. Durand (Kane's Voy.) includes U. minima, T. & G., 

 as well as pygmcea, Ilk. In Greenland it has been found only in the extreme north, by 

 Kane's Expedition, on Washington Land, lat. 81° N. 



Sisymbrium sophioides, Fisch. This is nothing but an abnormal form of ^S*. Sophia, L., 

 with a remarkably corymbose inflorescence. It has hitherto been found only in high 

 northern regions. 



S. brachycarpum. Rich. This, which passes by insensible transitions into ^S*. canescens, 

 Nutt., which inhabits the same regions to the south, often approaches flnely-cut-leaved 

 states of S. Sophia. 



S. salsugineum, PaU. I have carefully compared with this the Ttirritis diffusa. Hook., 

 and have no doubt of their absolute identity. 



Erysimum UeraGiifolimn, L. Ruprecht (Fl. Sam.) refers this to E. strictimi, Fl. Wett., 

 and notices E. cheiranthoides, L., as occurring very close upon the arctic circle, almost 

 at the termination of the woody region. I am quite unable to discriminate between 

 these northern Erysima and their southern congeners, nor do I find any satisfactory 

 characters for them in books. Fries does not consider either the true Meraciifoliwm, L., 

 or cheiranthoides to be Lapponian; but E. alpiniim, Sm., is so, and is ranked by him 

 as an insufiiciently established species. Nylander (' Flora Helsingfors,' 31) mentions E. 

 alpinmn as a form of cheiranthoides, and keeps hieraciifoUimi distinct. Some idea of 

 the difficulty (impossibility ?) of distinguishing these species may be obtained by reading 

 Fries's notes (' Summa,' p. 148) and observing the synonyms quoted by Koch under E. 

 strictum. 



Braya alpiina, Sternb. I think there can be no doubt that B. glabella, Rich., and 

 dubia, Br., are both synonyms of B. alpina, Sternb., or, at the furthest, arctic forms of 

 that plant. I am quite unable to distinguish them by any good characters. The pods 

 are singularly variable in length and breadth, and, as with other arctic Cruciferce, are 

 apt to be arrested by cold in early states of development, and hence to assume at later 

 periods various forms, depending on subsequent accessions of heat and moisture. 



Braya rosea, Bunge. I have retained this species, though I extremely doubt its distinct- 

 ness from B. alpina. The Arctic European habitat is introduced on the faith of Nyman's 

 ' Sylloge,' who quotes Bunge (Cat. Sem. Dorp., anni 1839) for its being a native of Arctic 

 Russia (Samojed.) ; but I do not find any of the genus in Ruprecht's Flor. Saraojcd. 

 Cisural. (1845). 



Braya pitosa. Hook. I have repeatedly examined this form very carefully, and, though 

 undoubtedly very near B. alpina in general appearance, I am unable to identify it with 

 any state of that plant. 



