162 American Midland Naturalist Monograph No. 6 



2a. Atrichum undulatum var. minus (Lamarck and DeCandolIe) 



Weber and Mohr 



Plate XXXI 



Differs from the species in having the stem, leaves and sub-erect capsule 

 shorter; lamella covering 1/7-1/5 of median part of leaf. 



Erie Co.: Presque Isle, May 8-9, 1906. O.E.J, (figured). Fayette Co.: Ohio 

 Pyle, May 30-3!, 1908. O.E.J. 



2b. Atrichum undulatum var. allegheniense (Jennings) 

 New Combination* 



Plate XXX 



Similar to the species in general habit and appearance but usually some- 

 what smaller and more slender: the lamellae 5-7 in number, usually 6, ranging 

 from. 4-7, usually 6, cells in height, the costa and lamellae together occupying 

 from one-sixth to one-third of the width of the upper part of the leaf; the 

 upper leaf -cells about .016-.018 mm in diameter. 



This variety is much more abundant in the Pittsburgh district than is the 

 species, evidently preferring habitats with shales and sandstones such as those 

 of the Carboniferous. 



Now known from the following counties, thus far apparently avoiding the High 

 Plateau: Allegheny, Armstrong, Beaver, Butler, Crawford, Erie, Fayette, Lycoming, 

 Somerset, Washington, and Westmoreland. Type specimen: Power's Run. across from 

 Verona, Allegheny County. O.E.J. April 18, 1906 (figured). 



3. Atrichum angustatum (Bridel) Bryologia Europaea 



{Polytrichum angustatum Schwaegrichen; Catharinaea angustata Bride! ) 



Plate XXXI 



Loosely cespitose: stems erect, about 1-3 cm high, or more; lower leaves 

 minute, the size of leaves increasing upwards, dull green, much crisped when 

 dry, lance-linear, doubly serrate from about the middle upwards along the 

 margin and dorsally towards the apex; costa with about 5-8 ventral lamellae 

 above, the costa and lamellae together occupying about one-fourth to one-half 

 of the width of the leaf; lamellae 6-8 cells high, cells equal in size; basal leaf- 

 cells elongate- rectangular, rather incrassate, about .010-. 025 mm in diam- 

 eter, above becoming quadrate, towards the apex slightly smaller more 

 or less hexagonal with the longer diameter transverse, about .010-. 015 

 mm: seta erect, about 1.5-3.5 cm long, smooth, lustrous, castaneous, somewhat 

 sinistrorse; capsule lustrous, castaneous, linear-cylindric, usually slightly curved, 

 abou: 5-8 x 1 mm; peristome-teeth obtuse, about 2.5 mm long; calyptra cucul- 

 late, slenderly rostrate, about 4-7 mm long; operculum hemispheric, slenderly 

 rostrate, about 2.5 mm long and more or less abruptly divaricately bent; spores 

 about .012-.018 mm, pale, orange-pellucid, smooth to minutely roughened, 

 somewhat incrassate, mature in late fall and winter. 



■'' Frye, in Grout's Moss Flora, regards this as synonymous with the preceding A. 

 undulatum var. minus. 



