128 NORTH AMERICAN FLORA [VoLumE 15 
above the greatly broadened base about 100 » wide and one twelfth the width of the leaf, in 
cross-section showing usually a double row of guide-cells, with stereid-bands above and below, 
the outer cells differentiated at least on the under side ; alar cells brownish or hyaline; inner 
basal cells hyaline, the cells above elongate with thickened pitted walls throughout, the intra- 
marginal ones occasionally of a double layer in the upper part of the leaf and bearing scat- 
tered teeth on the dorsal side; inner perichaetial leaves shorter than the stem-leaves, from a 
convolute base abruptly narrowed to a more or less serrulate point of variable length: setae 
aggregate, mostly yellow or brown, 2.5-4 mm. long: capsule comparatively small, 2.5-3 mm. 
long, nodding to horizontal, scarcely furrowed when dry; annulus wanting; lid with a slender 
beak, mostly longer than the capsule; peristome-teeth 125 » wide at the base, dark-reddish, 
vertically striate, the articulations on the inner face prominent, divided about one half down 
into 2 or 3 forks: spores slightly rough, up to 21 « in diameter. 
TYPE LocaLity: England. 
Distripurion: Greenland to Maine; Alaska; also in Europe and Asia. 
Exsicc.: Macoun, Can. Musci 35. 
Dicranum majus. orthophyllum A, Br.; Milde, Bryol. Siles. 71 ¢1869), with rather shorter, nearly 
straight leaves, should perhaps be considered a distinct species. I have not seen European speci- 
mens. Specimens so called, from Alaska, have been quite frequently collected and they have a 
single row of guide-cells in the costa. However, leaves from plants that seem to be typical D. 
majus show a remarkable variation in the costal cells and there seems to be no difference in the 
fruit of the two forms. 
26. Dicranum rugosum (Hoffm.) Brid. Bryol. Univ. 1: 414. 1826. 
Bryum rugosum Hofim. Deuts. Fl. 2: 39. 1796. 
Dicranum undulatum Ehrh.; Hoffm. Deuts. Fl. 2:39, assynonym. 1796, 
Dioicous: male rlants minute, on tomentum of the fertile stems, the perigonial leaves up 
to 2 mm. long, not undulate, abruptly narrowed to a lanceolate, serrulate, acute point, the 
faint costa often vanishing in the upper haif of the leaf; antheridia 4 or 5, about 0.4 mm. long, 
with few paraphyses: fertile plants in extensive, loosely cohering, mostly glossy, light-green 
tufts, with robust stems up to 20 cm. high, conspicuously thickened with dense tomentum 
extending almost to the apex and grayish above, rusty-brown below: stem-leaves long-lanceo- 
late, undulate, acute, up to 10 mm. long and 1.5 mm. wide, spreading-flexuous, subsquarrose or 
somewhat curved-secund, sharply serrate on the borders one half down and more or less recurved 
below on one or both sides; costa vanishing below the apex, a little above the base 100 » wide 
and one tenth to one twelfth of the leaf-width with two sharply serrate wings on the back above, 
in cross-section scarcely one half up the leaf showing about 6 guide-cells with stereid-bands 
above and below, and about two outer cells differentiated on the dorsal side, forming ribs; alar 
cells golden-brown, those within often hyaline, extending rather more than one half way to the 
costa, the cells in the blade above smooth, elongate to the apex, with thickened, pitted walls, the 
median ones about 12 « wide and 40-60 » long; perichaetial leaves closely convolute, rather 
longer than the stem-leaves, very faintly costate above the middle, abruptly narrowed to a 
slender, nearly smooth or sometimes serrate point often not more than one sixth the broader 
part in length: setae aggregate, 1-7, mostly yellow, 2-3 cm. long: capsule cylindric, 2-3 mm. 
long, curved, nodding to horizontal, smooth or irregularly furrowed when dry, not strumose, 
with few stomata in mostly one row; annulus wanting; lid obliquely rostrate, often longer than 
capsule; peristome-teeth about 400 u« long, finely and indistinctly vertically striate, papillose on 
the margins, divided sometimes almost to the base: spores somewhat rough, about 20 » in 
diameter. 
TyPE LocaLity: Germany. 
DISTRIBUTION: Newfoundland to British Columbia and southward to West Virginia, Ohio, and 
Oregon; also in Europe and Asia. 
Exsice.: Sull. Musci Allegh. 156; Sull. & Lesg. Musci Bor. Am. 69; ed. 2. 87; Drummond, 
Musci Am. 85; Aust. Musci App. 97; Holz. Musci Acroc. Bor. Am. 134. 
27. Dicranum frigidum C. Mill. Bot. Zeit. 17: 219. 1859. 
Dioicous: male plants minute, 2-3 mm. high, growing in clusters on the tomentum or 
_ sometimes on the older leaves of the fertile stems, the 5 or 6 antheridia with few paraphyses: 
fertile plants in extensive, soft mats, tomentose within, with robust stems up to 18 cm. high: 
