DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 329 
which the petals are often as short and of the same shape as in Ruprecht's plant, and 
s cauline leaf wanting. I doubt much if JP. Kotzebaei is really distinct. 
Saxifraga Aizoon, Jacq. Koch, Fries, and most authors keep this distinct from S. 
Cotyledon ; but I must own that I cannot satisfactorily discriminate their forms or make 
them tally with their assigned habitats, and am thus obliged to treat them as one plant. 
Both, according to Fries, grow in Lapland and Western Europe generally. Cotyledon 
alone is stated to be Icelandic ; Aizoon, which alone is Greenlaudic, Labrador, and Ts . 
American, is nowhere stated to occur in the Russian dominions. 
S. ccespitosa, L. It is not my purpose to enter into the disputed question of the limits 
of the members of this aggregate collective species. I have repeatedly examined all, and 
found innumerable grades connecting the most dissimilar, such as exarata and zileni- 
tra. Almost all are high arctic. S, unifora is the same as venosa, and is referred by 
Torrey and Gray to ccespitosa, to which S. Gramlaudica is reduced by almost all authors. 
S. exarata, Vill., is kept distinct in 'Flor. Bor.-Am.' (with an appended observation 
regarding the difficulty of distinguishing it), as also by Torrey and Gray, Ledebour, and 
most authors. S. muscoides, Wulff., is the common Middle and S. European form. 
i 
S. silemflora is confined to Arctic America; and JfagelUmiea, in a form identical a\ it 
exarata, does not extend in S. America north of Peru. 
S. controversy Sternb., which, according to most authors, is a synonym of adscendens, 
has been found on the Rocky Mountains by Bourgeau and Hector during Palliser's Expe- 
dition, but nowhere else in Continental America. 
S. exilis, DC. This, as suggested in * Elor. Bor.-Am.,' is, so far as may be judged by 
specimens tallying with the description, certainly only a weedy state of cernua. 
S. bulbifera, L. Koch distinguishes this from granulata by its leafy cyme and other 
characters that appear to be clearly connected with its being a bulbilliferous condition of 
& granulata, between which and bulbifera I find intermediate grades. Ledebour and 
Fries also keep it distinct. It is not Arctic Lapponian, but Russian. 
S. hyperborea, Br., is referred to rivulark /3 in ' Flor. Bor.-Am.' and by Torrey and Gray ; 
it is often a starved high-arctic form, but not a permanent or well-marked one ; it is con- 
fined to Arctic America, and Greenland. 
S. coriacea, Adams. This appears to me, from the description, not to be distinct from 
nivalis. I have seen no authentically named specimens. 
S. reflexa, Hook. This is certainly only Virgimensis, of which several specimens from 
the Rocky Mountains precisely accord with the arctic. 
S. hieraciifolia, W. & K., though Arctic Russian, fid. Ledebour, is not Lapponian, 
according to Fries. 
S.foliolosa, Br. This is a monster, as pointed out by Fries {comosa), rather than a 
variety proper, the foliaceous cyme and bulbilli being produced at the expense of the 
inflorescence proper. Ledebour reduces it, and Rupreeht notices its transition to stella- 
ris, L. 
S.propinqm, Br., is identified with Sirculus, L., in < Flor. Bor.-Am.' and by most suc- 
ceeding authors. 
