40 Morten P. PORSILD. 
Besides the characters mentioned above, there are several of less 
value, because they seem to be less constant, viz.: 
O. quadripetalus Git. O. microcarpus Turcz. 
(= O. paluster PERS.) 
several flower-stalks single or in pairs 
pubescent bracts glabrous 
ciliate calyx-lobes glabrous 
pubescent on edges, naked filaments pubescent all over 
on outer side 
longer than the tubes or fila- anthers shorter than the tubes or fila- 
ments. ments. 
It is of far more importance, however, as also SAMUELSSON empha- 
sizes, that the two species are ecologically different. According to 
E. Metin, ("Studier Over de Norrländska Myrmarkernas Vegetation’, 
etc. Uppsala 1917, p. 124 ff.), ©. mierocarpus is bound to a certain, 
well-defined association of species having Sphagnum fuscum and a 
few other xerophilous species of Sphagnum as its substratum. O. mi- 
crocarpus is thus what Braun-Blanquet!) calls “gesellschaftstreu” (in 
French: “exclusif”), whereas ©. quadripetalus is at most “gesellschafts- 
hold” (préférant), or even “gesellschaftsvag” (“indifférent”), as it grows 
on several, ecologically widely different species of Sphagnum, as well 
as on Hypnaceae or other substrata. 
Plants with some of the characters verging towards O. quadripe- 
talus have sometimes been supposed to be hybrids, but SAMUELSSON 
states (1. c.) that actual hybrids are very rare: 
Obgleich ich beide hundertmal gesehen habe, so bin ich in der Natur nur einmal 
auf eine wahrhaft kritische “Zwischenform”, und zwar betreffs aller oben bespro- 
chenen Merkmale, gestossen, und sie kam tasächlich mit beiden Arten zusammen 
vor, weshalb ihre Bastardnatur sehr wahrscheinlich ist. 
O. microcarpus Turcz. is quite common in Northern Europe, from 
Iceland to Russia, also in the Alps, and in Northern Asia to Sachalın. 
From America, I have not seen it reported, but a specimen from Wrangel, 
Alaska, collected by Fr. V.CovıLıe and Tx. H. Kearney (Har- 
RIMAN Expedition Nr. 436) undoubtedly belongs here. In well-in- 
vestigated countries, as the Scandinavian peninsula and Finland, 
O. microcarpus evidently ranges somewhat farther north and to higher 
altitudes than O. quadripetalus. 
1) For the explanation of these terms see f. inst., BRAuN-BLANQUET: Prin- 
zipien einer Systematik der Pflanzengesellschaften auf floristischer Grundlage. 
Jahrb. St. Gall. Naturh. Ges. 57. II. 1921 and E. RuEBEL: Ueber die Entwicklung 
der Gesellschaftsmorphologie. Journ. of Ecology 8. 1920, where numerous other 
papers on this subject are mentioned. 
