1909. No.8. VASCULAR PLANTS COLLECTED IN ARCTIC NORTH AMERICA. II 
Flowering specimens were collected on July 31st 1904 and Aug. 4th 
1005; no fruits developed. 
The name of this form of Cerastium which is closely related to 
C. alpinum L. and C. Edmondstonii (Wats.) Murs. & Ostr. (= €. arcticum 
LANGE, ex parte) has caused me much trouble. 
The characters separating our species (see Fig. 11) from the two others 
are the following: leaves small and short, mostly broadly elliptic or broadly 
ovate (rarely elliptic or elliptic- or ovate-lanceolate), in the sterile shoots 
close together, often imbricate, obtuse; in the flowering shoots few and 
separated, pair from pair, by long internodes, sometimes more or less acute; 
lower parts of the plant mostly glabrous, upper parts pubescent and 
glandular; bracts with + membranous margins; flowering shoots in the 
more reduced forms one-flowered, in the better developed forms rather 
richly dichotomously branched, but only at the top; flower-stalks 1—2 times 
as long as the flower, capillary; sepals 4.5—5.5(—6) mm. long, broadly 
ovate, obtuse, with membranous margins and mostly tinged with reddish- 
violet on the outer side; petals about twice as long as the sepals, emar- 
ginate. The specimens have often an extremely densely tufted and com- 
pact growth, and in such specimens the flowers are but few in numbers 
or quite wanting (f. cæspitosa MaLmGr. sub C. alpino). 
In 1862 A. J. MALMGREN (I. c.) drew attention to a peculiar Cerastium 
growing commonly in Spitsbergen in bare places; he named it C. alpinum, 
y, cæspitosum and said that he should have taken it for a good species, 
if a most obvious series of transitions to C. alpinum did not occur. 
Later (in 1900) GUNNAR ANDERSSON and H. HESSELMAX in their list of the 
flowering plants of Spitsbergen also report that there is a complete tran- 
sition from the main species — here C. Edmondstonii — to MALMGREN's 
form, which they take as the glabrous form of C. Edmondstonii (1. c. p. 58), 
but they add, that they cannot say, if the transition forms are the relicts 
of an evenly and slowly working variation or if they are due to hybri- 
disation (l.c., p. 61). I have seen much material of this Spitsbergen- 
plant — also specimens collected by Matrmcren himself — and further 
many specimens of just the same form from other countries, viz. Novaya 
Zemlia, Arctic Siberia, and now from King-William-Land (the specimens 
collected by the Gjöa-Expedition agree fully with specimens from the 
eastern arctic hemisphere), but I have never seen any transition to C. alpı-. 
num or to C. Edmondstonii. Formerly I myself believed that MALMGREN’s 
plant was a variety of C. Edmondstonii, but it differs from the latter 
mainly in the smaller sepals (4,5—5,5 mm. against 6,5—8 mm.), its inflo- 
rescence branched at the top, capillary flower-stalks, small, obtuse and 
