IOI — 
NOTES ON POLYTRICHUM COMMUNE. 
J. Franklin Collins. 
(Reprinted by permission from “Preliminary Lists of New England Plants” in Rhodora, 
8: July, iqo6.) 
No species in the list has been more difficult to interpret than Poly- 
trnchum commune with its many forms and variations. The species, as 
described by Dillenius, Linnaeus, Bruch and Schimper, Dixon, Limpricht, 
Roth, Lesquereux and James, and others, appears to be much less common 
than has been generally supposed. It is impossible at the present time to 
place satisfactorily some of the forms of this species, yet certain conclusions 
have been reached which would seem to justify preliminary publication, 
especially as it is very desirable that the attention of collectors be called to 
the necessity of getting abundant material from various habitats and locali- 
ties— more particularly perhaps from bogs, swamps, and other wet places. 
The writer would be very glad to get specimens from any and all parts of 
the country— especially from New PJngland — with a view of attempting to 
clear up the uncertainty in regard to several varieties and forms, the identi- 
ties of which are at present too problematical to appear in the above list. It 
is quite possible that the interpretation of P. commune, as outlined here, may 
have to be revised when more material is at hand. Briefly, P. commune , as 
here restricted, is the fairly tall plant of moist shaded places with the game- 
tophyte normally at least io cm. high, stems mostly simple, leaves remote, 
the upp-er free part (blade) about i cm. long and appressed when dry but hav- 
ing the apex recurved and the shining leaf-bases conspicuous; seta 6-n cm. 
and capsule 5 mm. (4-7) long ; calyptra golden brown. 
The var. perigoniale is a smaller plant (-4-8 cm. high) of drier and more 
exposed situations, with leaves smaller and more crowded, so that, when 
dry and appressed, the leaf-bases are ordinarily not seen: seta and capsule 
shorter (the latter 3-4 mm. long). As a rule this variety is darker colored 
in all its parts and more compact than is the species, suggesting a more xero- 
phytic plant. The perichaetial leaves, although usually more conspicuous 
and more prominently hyaline, are not necessarily any larger than in the 
species. This variety undoubtedly occurs in Vermont though no record of 
its occurrence there has been found. 
The var. uliginosum is just such a variation as might be expected in a 
very moist, well shaded, and humid situation; that is, with elongated and 
more or less flexuous stems, longer and most distant leaves. In the dried 
state a very pronounced character is the abruptly squarrose upper portion of 
the leaf, the apex of which is often somewhat recurved or even circinate. It 
should be expected in all the New England states. 
From an examination of some thousands of leaf sections of P. commune 
and its allies during the past year it is quite evident that there is much more 
variation in the lamellae than might be expected from reading standard 
descriptions; for instance, the end cells in sections may vary from strongly 
crescentric to circular in the same leaf, depending respectively upon whether 
the section is cut near the middle of the leaf or down near the sheath. Like- 
