Fragile Leaf Dicranum Moss

Dicranum fragilifolium Lindb, Oefv. Sv. Vet.-Akad
Forh. 14: 125. 1857.
Dioicous: malejrfants slender, up to 6 mm. high, growing, often 2 or 3 together, on tomentum of the upper fertile stems and bearing 1-3 flowers, each with 4 or 5 antheridia about 0.5 mm. long and few paraphyses, the perigonial leaves, mostly distinctly costate, from a brown base abruptly narrowed to a long, slender, more or less serrulate point: fertile plants in compact, mostly pale-green tufts, with slender stems up to 9 cm. high, tomentose to near the apex: stem-leaves erect-spreading, somewhat flexuous above, 6-7 mm. long, narrowly lanceolate and gradually long-subulate, from entire to more or less rough on the margin and back toward the apex, the fragile, often broken, nearly straight, grooved point mostly filled by the excurrent costa; costa one third to one fourth the width of the lower part of the leaf, in cross-section below showing 8-12 guide-cells with stereid-bands above and below, each of about two rows of cells of mostly uniform size ; alar cells brown to hyaline, extending to the costa 1 ; lower leafcells elongate with slightly thickened and pitted or not pitted walls, becoming shorter and not pitted above, the upper ones about 8 n wide and from nearly square to 2 or 3 times as long as broad; perichaetial leaves from a convolute base rather abruptly narrowed to a slender, smoothish point as long as the clasping part: seta 1.5 cm. long, finally reddish: capsule about 2 mm. long, oblong, curved, nodding, not strumose, furrowed when dry; annulus of mostly 2 rows of cells; lid conic-subulate, about as long as the capsule; peristome-teeth brown, vertically striate nearly to the apex, divided about one half down: spores rough, up to 25 ^ in diameter.
Type; locality: Sweden.
Distribution: Labrador to Alaska and southward to Minnesota, Montana, and' British Columbia, on logs; also in Europe and Asia.