170 American Midland Naturalist Monograph No. 6 



From the Arctic regions of North America south to North CaroHna; 

 southern South America; northern Europe and Asia. In bogs or boggy woods. 



Rar^ in our region. Crawford Co.: In small Cassandra bog near Linesville, May 

 28, 1908. O.E.J, (figured). Washington Co.: Hanlin, in tuft of Leucobryum. May 

 21, 1908. O.E.J. 



6. PoLYTRlCHUM COMMUNE Linnaeus, Hedwig 

 Plate XXXIII 



Large, erect, 10-20 cm high, loosely cespitose in large masses, rather dark 

 olive green: stems simple, flexuous, woody, slightly or not tomentose at base, 

 chestnut-brown, rather densely foliate above; lower leaves small, linear, becom- 

 ing gradually larger above up to about 15 mm long, the limb linear-lanceolate 

 from an oblong sheathing base, when moist spreading or recurved, when dry 

 appressed-erect, serrate to the sheathing base, the apex linear, serrate, pellucid; 

 areolation at base of sheath parenchymatous, rectangular, above becoming 

 linear-prosenchymatous, abruptly grading at base of limb into rounded incras- 

 sate cells about .0I0-.015 mm in diameter, towards apex becoming elliptic 

 with the longest diameter transverse, all pellucid to more or less opaque; 

 lamellae 40-60, 4-9 cells high, the terminal cell broader and retuse to bi-cus- 

 pidate at apex, the lamellae extending almost to the base of limb; perichaetial 

 bracts up to 20 mm long, with a longer sheathing portion and few or no 

 lamellae; antheridial flowers conspicuous, cup-shaped, the broadly obovate 

 shortly acuminate bracts which form the cup being about 4 mm long, the costa 

 broad and weak below but stronger and bearing numerous lamellae in the 

 upper half; the successive annual growths of the male plant taking place from 

 the center of the antheridial flower of the preceding season: seta wiry, flexuous, 

 6-10 cm long, lustrous, chestnut to light golden-brown; capsule erect, but later 

 inclined, and, when old and empty, cemuous, light to deep chestnut-brown, 

 more or less cubial or shortly rectangular, apophysis discoid, distinct; capsule- 

 urn about 3-5 mm long; operculum low-conic, the beak about 1 mm long, 

 straight or curved; peristome-teeth about .25 mm high, more or less reddish- 

 pellucid; exothecial cells hexagonal, the outer face convex and with a rounded 

 to elliptic pore; spores round, smooth, about .008-. 010 mm, mature in mid 

 summer — calyptra covering the whole capsule, rather lustrous, yellowish-brown. 



Cosmopolitan; in North America almost throughout, in marshy places, 

 pastures, woods, etc. 



Now (1942) known from every county in western Pennsylvania except Blair, Clarion, 

 Forest, Fulton, Himtingdon, Indiana, and Venango, but probably occurs in all. Sp>eci- 

 men figured: Near Hartstown, Crawford Co., in wet meadow, June 28, 1908. O.E.J. 

 This is the form which some authorities recognize as var. uliginosttm Huebener, as 

 follows: 



6a. PoLYTRiCHUM COMMUNE var. ULIGINOSUM Huebener 



Plate XXXIII 



In this variety the stems are less strong and rigid than in the species, and 

 the leaves in the dry specimens are wide-spreading to recurved. It is rather 

 rare in the eastern part of the United States. Perhaps not sufficiently distinct. 



