DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 331 
Ptarmica alpina, L. The numerous plants here brought together do not differ more 
inter se than do the forms of P. vulgaris (with which this is intimately connected), and 
they are further all united by intermediate forms. P. alpina itself is found in Arctic 
Siberia and the Altai ; P. oxyloba is only known in Arctic Siberia. P. speciosa, DC. : 
Ledebour rightly remarks that this is rather a form of vulgaris than a species. P. mul- 
tifiora, Hk., was originally referred to a var. of vulgaris, from which it differs in its deeply 
cut leaves, and broad-, short-ligulate flowers. P. Sibirica, Led., is confined to East Siberia 
and Escholtz Bay. Of the borealis, Bong., of Sitcha, I have seen no authentic specimens. 
Chrysanthemum Sibiricum, Turc, is retained by DC, Ledebour, &c, but apparently 
on very slender grounds. 
C. integrifolium, Rich., is an eminently northern form, not found west or north of the 
Tchuktchi country, and scarcely south of the polar circle ; it may prove to be connected 
with leucanthemum by intermediate forms. 
C. leucanthemum, L., is not Lapponian, but Arctic Russian. C. Segetum is occa- 
sionally found in Nordland, but apparently rather as an alien than a genuine arctic 
plant. 
Pyrethrijm pulchellum, Turc, is certainly identical with the small arctic form of ino- 
dorum ; and Fries adds as a variety the P. cmbiguum, Ledeb., correctly. Ruprecht con- 
sidered the woolly hairs on the peduncle of P. pulchellum sufficient to distinguish it; but 
this is not the case. 
Artemisia Tilesii, Led. Fries ranks this as a var. of vulgaris, L., both being found in 
Lapland. Seemann remarks that they occur together throughout Western Eskimo-land. 
A. Chamissoniana, Bess., is reduced to arctica, Less., in ■ Flor. Bor.-Ani./ and by most 
succeeding authors. A. Norvegica, Fr. : in the * Flor. Bor.-Am.' it is stated that this 
is identical with A. Chamissoniana; on comparison I find it has rather larger capitula, 
but is not otherwise different ; it is a very rare alpine plant in Norway, not entering the 
arctic circle. 
A. globularia, Cham. I think this is quite the same with glomerata ; both are con- 
fined to the country around Behring's Straits. 
A. androsacea, Seem. This is a remarkable and very local plant, which I cannot identify 
with any more southern species, though, judging from analogy, I suspect that it may 
eventually prove only an arctic tufted variety of some better-known plant. 
A. ccespitosa, Bess. I have seen no specimen of this ; but, judging both by plate and 
description, I do not doubt that Torrey and Gray's surmise is correct as to its being the 
same with Richardsoniana. 
A. Canadensis, Mich. This, according to Richardson, advances to the arctic circle 
east of the Rocky Mountains. After a careful re-examination I cannot doubt its identity 
with A. desertorum, Spr., as also certainly with commutata (5. Gebleriana, Bess, in 
Herb. Hook. Canadensis is the earliest name. 
Bidens tripartita, L., is not found in Arctic Lapland, though it enters the arctic circle 
R 
I am quite unable to distinguish the American B. connata, Muhl 
yol. XXIII. 
2 Y 
