Jennings: Manual of Mosses — I. Sphagnales 31 



ranging from 1-2 mm long, when dry, with undulate margins, flexuose and with 

 a recurved apex, when moist straight and erect-appressed, tapering to a rather 

 narrowly obtuse apex with two or three teeth, the margin involute above; hyaline 

 cells of branch-leaves fibrillose and porose, above the midde rather narrow, 

 ventrally usually with large pores in the cell-angles of about one-third the width 

 of the cell, dorsally with small end-pores or sometimes a very few rather dis- 

 tinctly ringed lateral ones; in cross-section the hyaline cells are ventrally quite 

 convex, the chlorophyllose cells triangular or rarely trapedoidal, usually ex- 

 posed only on the dorsal face; perichsetical leaves large, broadly oval, concave, 

 pointed: spores smoothish, yellow, about .025 mm in diameter. 



A cosmopolitan species occurring in North America from Newfoundland 

 to Labrador and south to the Gulf States. 



This is probably our commonest sphagnum, occurring not only around the borders 

 of bogs but out in seepage areas in open] hillside fields. It is now known from seventeen 

 counties in western Pennsylvania, most of the records being from the southwestern and 

 northwestern parts of our area. The following variety amblyp.hyllum seems to be the com- 

 moner form in the central uplands and mountains. Figured from specimens collected May 

 29-31, 1910, around Mud Lake, Hartstown, Crawford County, O.E.J. & G.K.J. 



10a. Sphagnum recurvum var. amblyphyllum (Russow) Wamstorf 



(S. amblyphyllum Russow) 



TTie variety has the stem-leaves more spatulate-triangular, with a more 

 rounded and somewhat erose-denticulate apex; the cuticular sheath is less 

 plamly differentiated and the cells are more incrassate than in the typical form 

 of the species. All possible intergradations seem to be represented among the 

 specimens examined. It may usually be recognized when dry by the strongly 

 undulate branch-leaves, these usually still remaining undulate when mounted 

 wet for examination under the microscope. 



Now known from eight counties from Centre west to Crawford and Allegheny coun- 

 ties through the middle of the area. 



10b. Sphagnum iRFXURVUM var. tenue Klinngraeff 



(S. angustifolium Jensen; S. recurvum var. parvifolium Warnstorf; S. amblyphyl- 

 lum var. parvifolium Warnstorf; S. parrifolium (Sendt. ) Warnstorf) 



Plate VI 



Softly and loosely cespitose, yellowish- to grayish-green, or brownish above: 

 stems slender, usually at least 10-12 cm high, the wood-cylinder yellowish and 

 without any distinctly differentiated cuticular sheath: stem-leaves small, usually 

 0.5-0.7 mm long, equilaterally triangular to somewhat triangular- lingulate, the 

 apex rounded or somewhat truncate, erose-dentate, the hyaline border narrow 

 above and very wide below; hyaline cells of stem-leaves non-fibrillose, non- 

 porose, a few septate towards the base on each side of the median region; 

 branches 3-5, two being slender and appressed-pendent, two or three short, 5-9 

 mm long, divergent, recurved at the tips; branch-leaves lanceolate, about 1 mm 

 long, concave, the uniformly narrowly hyaline-bordered margin involute 

 towards the narrowed, slightly truncate-erose apex, leaves when dry more or 



