318 DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 
unain speciem pertineant valde variabilem; interim tamen formas distinguere 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 Linnaeus, 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. Grcenlandica, with reniform, fleshy, quite entire leaves (generally small). 
Of these I find Grcenlandica so often passing directly into officinalis, both in America 
and Europe, that I have brought them together ; the others are more distinguishable pre- 
valent forms, though all pass into one another. 
Cochlearia sisymbrioides, 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. 
Cochlearia 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 Europe 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.). Durand appears to restrict this in Greenland to a form 
with elliptical pods and fenestrate septa. 
C. oblongifolia, DC. Ruprecht, I. c, observes that the form with elliptic silicles occurs 
almost everywhere on the Samoied beaches ; that with globose pods only at Cape 
Konuschin. 
C. fenestrate Br. Nyman (' Sylloge ') includes this under Wahlenbergii, Rupr. Durand 
(Kane's Voy.) distinguishes it by its smaller size. Pries makes it a var. of Anglica, L. 
Cochleauia officinalis, L. Nyman (« Sylloge,' p. 198) refers C. Grcenlandica, L., and 
Pyrenaica, 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 officinalis ( Wahlenbergii, Rupr.), also arctica, Lenensis, and fene- 
strata, Br., though the latter name has, I suspect, been rather indiscriminately applied to 
other Cochlearia} with ruptured septa. Durand defines the Greenland form by its glo- 
bose silicles. 
C. arctica, DC. Of this, Ruprecht 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 siliquse, from C. Anglica in the ellipsoid silicles (not subrotund), 
