276 American Midland Naturalist Monograph No. 6 



2. Plagiothecium Roeseanum (Hampe, mss.) Bryologia 



{Hypnum Sullivantiae Schimper; H. Roeseanum Hampe) 

 Plate LXXI 



Compactly cespitose, pale green to yellowish-green, somewhat shining; stems 

 more or less erect, sparsely branched, radiculose at base; leaves about 2 mm 

 long, somewhat crowded, sub-imbricate, ovate-oblong, abruptly and very shortly 

 acuminate, rarely slightly serrulate towards the apex, thin, concave, the leaves 

 hardly complanate, but the branches appearing julaceous; costa various, often 

 bifid, rather strong and long; median leaf-cells narrowly linear, about 10-15:1, 

 towards the base gradually becoming shorter and broader; perichaetial leaves 

 erect, the inner oblong, narrowly acuminate: capsule cylindric-oblong, erect to 

 sub-inclined, smooth and constricted at the neck when dry; lid conic, obliquely 

 i-hort-rostrate; annulus large, simple; peristome hypnoid, the two cilia strong 

 and about as long as the entire segments; spxjres mature in summer. 



This species apparently intergrades with P. denticulatum. The stems are 

 quite brittle and it is difficult to separate the leaves from them without break- 

 ing them. 



On stones and earth in moist or swampy woods; Eurasia, and from Nova 

 Scotia to Alaska and south to Georgia. 



Allegheny Co.: Powers Run, O.E.J. &C G.K.J. May 25, 1904 (named by F. E. 

 Wynn. 1944). Fayette Co.: On face of large rock, Laurel Run, Chestnut Ridge, 

 Dunbar Twp. C.M.B. June 16, 1940 (figured). 



3. Plagiothecium sylvaticum [Hudson, Bridel] Bryologia Europaea 

 {Hypnum silvaticum Bridel; H. denticulatum C. Mueller) 



PlatP LI 



Both this and P. Roeseanum are perhaps but varieties of P. denticulatum, 

 but until better known should probably be kept apart as separate species. 

 Tufts large, dull or but slightly glossy, deep olive-green to yellowish-green; 

 stems prostrate, stoloniferous; leaves rather soft, large, concave about 2-3 mm 

 long, not very regularly complanate, widely sperading, shrinking and somewhat 

 twisted when dry, broadly ovate-lanceolate, narrowed considerably towards the 

 decurrent base, tapering abruptly to the acute, entire or obsoletely denticulate 

 apex, plane-margined: costa rather faint, double, often reaching one-third the 

 length of the leaf: median leaf-cells about 8-10:1, about .016 mm wide, large, 

 hexagonal-rhomboid, the alar cells numerous and quadrate-oblong, sub-inflated, 

 hyaline and decurrent; perichaetial bearing rhizoids at base, about 3 mm high, 

 the leaves sheathing with a flexuous acumen, non-costate; seta castaneous, slen- 

 der, about 2-4 cm long, dextrorse above when dry; capsule yellowish, about 2 

 mm long, long-cylindric from a tapering neck, inclined, arcuate, smooth, but 

 when dry and empty somewhat striate; lid conic, acuminate to sub-rostrate, 

 about one-half as long as the urn; peristome-teeth bright orange at base, pale 

 above, lance-subulate, confluent at base, closely trabeculate, the dorsal lamellae 

 finely cross-striolate; segments slender, about as long as the teeth, narrowly 



