320 FRYE 
Named after Jensen.”® 
Plants lighter in color than P. commune. Stem 3-5 cm. high. 
Leaves about 8 mm. long, somewhat spreading when moist, but 
erect when dry, sheath to blade about as 1 : 2; apex blunter than in 
P. commune, dentate; a brown spot where sheath joins blade near 
vein. Margin plane below, erect or slightly incurved above, en- 
tire below, somewhat serrate in the upper half. Lamelle 30-35, 
6-8 cells high; marginal cells notched in cross section, smooth, 
thickened. 
Capsule 4-angled, width to length about as 1 : 14, smooth, porose. 
Teeth 64. Lid conic, with a short slightly crooked beak.2W— In 
Sphagnum bogs and on soil.—Nome, Alaska; Yellowstone National 
Park, Wyoming; Greenland; northern Europe. 








2 vd 
Fig. 25. Polytrichum yukonense. 
1 = Plant, X 1. 2 and3 = Leaves, showing lamelle on upper side, X 13. 4 = 
Cross section of leaf, X 34. 5 = Crosssection of a lamella, showing notched marginal 
cell, X 135. 6 = Portion of a lamella as seen from side showing irregularity of cell 
form and arrangement, X 270. (After Cardot & Thériot.) 
°C. O. E. Jensen is a Danish apothecary at Kirke Hvalsé, Denmark. 
” This is not a description of the plant, but a noting of some of the characters from 
specimens and verification of points from Asa Gray Bulletin and from Bryologist, 
4; p. 26. Literature containing Hagen’s description was inaccessible to the writer. 
