320 DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS 
Thlaspi montamim, L. I am quite unable to satisfy myself about the specific limits 
of this plant, and indeed of many other forms of the genus, whose species appear to be 
extravagantly multiplied. Belgium is its northern limit in Europe, whereas T. alpestre, 
to which the American plant may belong, reaches Gothland. 
* 
Lepidium ruderale, L. This widely-spread plant advances beyond the arctic circle in 
North-eastern America, but apparently not in West America or Europe. It is so fre- 
quently an introduced plant, that it is difficult to assign its indigenous limits. 
Subularia aquatica, L., though apparently not a native of the Alps, is found in the 
Pyrenees . 
Viola palustris, L. According to Eries, the typical plant of this name is rare and local 
in Lapland. Asa Gray identifies the White Mountain plant with it ; and it is also found 
in Southern Greenland. It is absent in Arctic Russia. 
V. epipsila, Led. Eries, in his « Novitige,' makes this a variety of palustris ; and in his 
1 Summa Veg. Scand.' it is regarded as a species found throughout Lapland. Koch 
keeps it distinct, but has never seen living specimens. Ruprecht (Elor. Samojed. 
Cisural.) mentions a variety hyperborea, in which the sepals are narrower and sharper 
than in the typical states, and the peduncles and petioles more slender. In the in- 
terior of the arctic Island of Kolgujew it is very rare, and has glabrous leaves. 
I am doubtful about the specific distinctness of this plant. It closely 
Wahl 
resembles V. palustris ; and A. Gray keeps it distinct, but his differential 
appear very trifling. In « Elora Bor.-Am.' the flowers of the two are said to present 
"the most perfect agreement." In « Bot. Beechey's Voy.,' V. blanda is said to inhabit 
Kotzebue's Sound ; and Ledebour, who has seen specimens, retains it with a query, 
and says that, though allied to V. palustris and epipsila, it differs in habit, smaller 
flowers, and approximate nodes of the root. Seemann does not include it in his Elora 
of Western Eskimo-land. The blanda is said to be fragrant. V. uliginosa, Schrad., 
is another species which is so excessively close to palmtris as to be with difficulty 
distinguishable. 
microeeras, Rupr., is founded on a solitary specimen from the shores of Kolgujew 
Island ; its author says of it, " facies tota V. palmtris, sed folia margine et paghia 
superiore (non inferiore) pubescentia ; sepala linearia, acuta, margine rigide ciliata, 
serrata. 
j> 
L. The various forms and near allies of this plant are sources of infinite 
diversity of opinion amongst botanists; added to which, reeardine canina and 
is a 
group designated Sylvestres by Eries, they seem to inosculate in many points with 
another and different one, the Pratenses, Eries. Thus it is not difficult to unite canina with 
Buppii and staynina, through the forms of what is often called lactea. Watson has soni< 
excellent remarks on these forms; he includes lactea, Sm., under flavicornis, and keeps it 
doubtfully distinct from canina. Eries considers montana, L., a distinct variety only of 
and gives all Lapland as the habitat for both, wher 
and sylvatica 
though also Lapponian, are more local : in his ' Novitije ' he makes sylvestris, Lam 
variety of canina, as does De Gingins in DeCandolle's ■ Prodromus.' Koch makes both 
