208 American Midland Naturalist Monograph No. 6 



spreading; stem-leaves more or less doubly plicate, from a more or less broadly 

 ovate base, lanceolate to lance-subulate, the margin revolute at base, the upper 

 margin indistinctly serrulate to entire; costa strong, sometimes percurrent, 

 sometimes excurrent, mostly smooth; cells more or less pellucid, oval to oblong- 

 hexagonal, with one papilla over the lumen, the alar quadrate; branch-leaves 

 narrower at the base, shorter- pointed, plane- margined, more or less distinctly 

 serrate, with a single terminal papilla on the apical cell; costa shorter, cells 

 mostly opaque; inner perichaetial leaves erect, pale, plicate, from a lanceolate 

 or linear base long-acuminate, incompletely costate: seta 1.5-2.5 cm long, 

 red-castaneous, smooth; capsule inclined, oblong-cylindric, drying more or less 

 horizontal and arcuate, v hen old and empty contracted below the mouth; 

 annulus present; peristome-teeth lance-subulate, yellow, bordered, transversely- 

 striate, dorsally lamellate; inner peristome yellowish, the basal membrane wide 

 and carinate, the segments lance-subulate, of same length as teeth, carinate, 

 entire or narrowly split, cilia complete, 2 or 3, slender, nodose or appendicu- 

 late; lid convex-conic; acute; calyptra cucullate; spores .008-.012 mm. 



A genus of nearly 50 species, mostly occurring in eastern Asia and in 

 South America; only the following in our region. 



Key to the Species 



A. Stem-leaves rounded-ovate, short-acuminate; margins erose-serrate 1. H. virgin'tanum 



A. Stem-leaves ovate, more or less long-acuminate; entire to crenulate serrate 



2. H. m'crophyllum 



1. Haplocladium virginianum (Bridel) Brotherus 



(Thuidium virginianum Lindberg; T. gracile var. lancastriense Cardot; Hypnum 

 gracile var. lancastriense Sullivant and Lesquereux) 



Plate XXXIX 



Small to medium-sized, appressed-cespitose, dark to dirty green: stems 

 diffusely divided, the branches short and erect or ascending pinnately; leaves 

 of the stems rounded-ovate, concave, narrowed to the base but scarcely decur- 

 rent, about 0.6-0.8 mm long, abruptly acuminate, costate into the acumen, 

 serrulate above, erose-dentate below, appressed when dry, loose when moist; 

 costa ending in the apex; median leaf-cells quadrate-hexagonal, uni-papillate, 

 rather incrassate, the lower marginal more or less transversely oblong-quadrate 

 or hexagonal; branch-leaves about 0.4-0.6 mm long, broadly and shortly acu- 

 minate with a serrulate margin above; perichaetial leaves long, pale, up to 2.5 

 mm long: seta slender, about 2-2.5 cm long, rather richly castaneous, dextrorse; 

 capsule oblong-cylindric, castaneous, curved, more or less horizontal, often 

 when old more or less pendent by the curving of the upper part of the seta, 

 annulate, the urn about 2.5:1, about 2 mm long, constricted below the mouth 

 when dry and empty; lid obtusely short-beaked, about one-third as long as the 

 urn; peristome normally hypnoid, yellowish, the 16 teeth lance-linear, dorsally 

 cross-striate, with zigzag divisural line, distinct dorsal lamellae, and about 

 35-40 closely placed trabeculae; segments about as long as teeth, carinate; 

 cilia (1-) 2-3, nodose-articulate, the basal membrane about two- fifths the 

 height of the peristome; exothecial cells incrassate, quadrate to oblong-hexag- 



