318 DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 



unani speciem pertineant valcle vai'iabilem ; interim tamen formas clistinguere necesse 

 fuit." 



In endeavouring to dispose of the arctic forms of this genus I have found myself obliged 

 to return to the old species and definitions of Linnseus, who, as it appears to me, had a 

 definite idea of the following four prevalent forms : — 



C. officinalis, with cordate subrotund radical leaves, and oblong subsinuate cauline; 



C. Danica, with hastate, angular, deltoid, petioled leaves ; 



C. Anglica, with all the leaves ovate lanceolate ; 



C. GrcenlancUca, with reniform, fleshy, quite entire leaves (generally small). 



Of these I find Gt'oenlandica so often passing directly into officinalis, both in America 

 and Europe, that I have brought tliem together ; the others are more distinguishable pre- 

 valent forms, though all pass into one another. 



CocHLEABiA sisymhrioides, DC. This is much more distinct from any of the other arctic 

 forms than the most distinct of these latter are from one another. I know of no other 

 which at all approaches it, though the perfectly flat pod, so opposed to the prevalent 

 generic character, may be found in states of C. officinalis. 



CocHLEAKiA Danica, L. This, in its typical form of a small slender spreading plant, 

 with hastate, petioled, small leaves, is by far the most distinct of the group to which it 

 belongs. It is found on all the northern coasts of Evirope as far south as Brittany and 

 Normandy, and suddenly reappears in its typical state in the Pyrenees. According to 

 Fries it does not inhabit Lapland. 



CocHLEARiA Anglica, L. Watson confesses his difficulty in always distinguishing this, 

 which to him appears to pass on one hand into Danica, and on the other into officinalis. In 

 Western Europe it is common as far south as the Channel, but does not extend beyond 

 Boulogne (Gren. & Godr.). Dm^and appears to restrict this in Greenland to a form 

 with ellii^tical pods and fenestrate septa. 



C. oblongifolia, DC. E-uprccht, I. c, observes that the form with elliptic silicles occurs 

 almost everywhere on the Samoicd beaches ; that with globose pods only at Cape 

 Konuschin. 



C. fenestrata, Br. Nyman (' Sylloge ') includes this under WaUenbergii, Eupr. Durand 

 (Kane's Voy.) distinguishes it by its smaller size. Fries makes it a var. of Anglica, L. 



CoCHLEARiA officinalis, L. Nyman (' Sylloge,' p. 198) refers C. Grcenlandica, L., and 

 Fyrenaica, DC, to this. Watson (' Cybele ') confines it to shore plants with globose silicles, 

 doubtfully keeping distinct the mountain form C alpina. Sweet ?, Grcenlandica, With. ?, 

 Sm. It is a common mountain plant in Northern Europe, occurring as far south as 

 the Pyrenees and Carpathians, but it does not extend far down the French coast. It 

 includes Wahlenberg's q^cmaZ^* {JFalilenbergii, Eupr.), also arctica, Lenensis, and fene- 

 strata, Br., though the latter name has, I suspect, been rather indiscriminately applied to 

 other Cochlearice with ruptured septa. Dm-and defines the Greenland form by its glo- 

 bose silicles. 



C. arctica, DC. Of this, Euprecht remarks that the Samoied specimens have entire or 

 fenestrate septa, but that it differs from C. fenestrata, Br., in larger size (^-1 foot) and 

 distinctly-nerved sfliquse, from C. Anglica in the ellipsoid silicles (not subrotund). 



