THE POLYTRICHACE^E OF WESTERN NORTH AMERICA 301 



4. Pogonatum alpinum (L.) Roehl., in Ann. Wett. Gesells. Ill, p. 



226 (1812). 

 Polytrichum alpinum L., in Sp. pi. II, p. 1109, n. 2 (1753). 



Probably so named because it is found in mountain (alpine) regions 

 in Europe. 



Plants loosely or densely tufted, tall, decumbent at base. Stems 

 much branched, rarely simple. 



Leaves dull green, narrowly acuminate, not crisped when dry. 

 Margin serrate. Lamellae 30-40, 5-8 cells high; marginal cells 

 slightly larger than the others, ovate to ovate-conic, longer than 

 wide, thickened, papillose or rough, yellowish. 



Calyptra shorter than the capsule. 



Capsule inclined, arcuate, subglobose to elongate-cylindric and 

 curved, terete, narrower at mouth than below, smooth, with stom- 

 ates, greenish-brown, black and rugose when old; hypophysis in- 

 distinct or wanting. Peristome present; teeth 64, or 32 double 

 ones, short, irregular. Beak of lid curved, long, subulate. Pedi- 

 cel long, flexuous. On soil. From Kotzebue Sound north of 

 Bering Strait in Alaska southward to Washington and Idaho; 

 White Mountains of New Hampshire; Europe; Asia; Australia. 



COMPARISON OF VARIETIES WITH TYPE. 



4a. P. alpinum var. simplex 16 Sch., in Coroll. p. 91, (1856). 



i. Leaves about 5 mm. long. " 

 2. Leaf-sheath to blade about as 1 12 J. 

 3. Plant about 2 cm. tall or shorter. 

 4. Capsule i . 8-2 . 3 mm. long. 



5. Width of capsule to length as i : i-J 2j 

 6. Stems simple. 



7. Pedicel i|-2 cm. long. 



On soil and rocks. Port Clarence, Alaska; Colorado; Copper 

 Mountains and Gold range in British America. 18 



16 So named on account of its unbranched stems. 



17 It should be borne in mind that varietal differences are not so constant as those 

 characterizing species; varieties grade into each other more. Therefore, while these 

 numbered statements constitute a description and comparison of the varieties, con- 

 siderable latitude must be permitted for variations. 



18 An examination of Macoun's No. 427 leads to the conclusion that this is var. 

 simplex instead of var. septentrionale. 



