160 American Midland Naturalist Monograph No. 6 



leaves Ungulate to ovate-oblong, not sheathing nor narrowed above the base 

 but slightly embracing the stem, margined, serrate; crisped when dry, costa 

 narrow, on the upper side with 1-12 narrow lamellae, ending below or in the 

 apex, towards the apex often spinose-serrate; cells chlorophyllose, the upper 

 rounded-hexagonal, smooth, the basal mostly rectangular: seta long, erect; 

 capsule smooth, cylindric to oval, rarely obovate, often more or less curved; 

 operculum long-rostrate; peristome of 32 teeth with pale borders and a median 

 orange to reddish-brown line, the basal membrane narrow and reddish-brown 

 or orange; calyptra smooth except at the apex, where it is sometimes spinulose: 

 mostly dioicous. 



A cosmopolitan genus comprising about 40 species, growing on earth, 

 mostly in the temperate zones; about 20 species have been reported for 

 North America; four species in our region. 



Key to the Species 



A. Upper leaf-cells .015 to .025 mm, in diameter; costa and lamellae not exceeding one- 

 fifth of the width of the median part of leaf B 



A. Upper leaf-cells .007 to .015 mm in diameter; costa and lamellae e.xtending over 



one-fifth to two-thirds of the width of median part of leaf C 



B. Lamellae 3-6 in number and 3-6 cells in height, covering about 1/8 to 1/11 of the 



median lef-width 2. A. undulatum 



B. Lamellae 5-7 in number and 4-7 cells in height, covering about 1/7 to 1/3 of the 



median leaf-width 2a and 2b. A. undulatum var. minus 



B. Lamellae 0-4 in number, 1-3 cells high; leaves crispate when dry 1. A. crispum 



B. Lamellae 4-6 in number, 6-13 cells in height - {A. undulatum var. Sdwyni) 



C. Lamellae 4-7, 6-9 cells high, covering 1/3 to 1/4 of median leaf-width 



3. A. angustaturn 



C. Lamellae 6-8, 8-14 cells high, covering about 1/5 to 1/3 of median leaf-width; 



upper cells papillose 4. A. papillosum 



C. Lamellae 7-12, 8-14 cells high, covering about 1/2 to 2/3 of median leaf-width 



5. A. angustaturn var. plurilamellatum 



1. Atrichum crispum (James) Sullivant 



(Catharinaea critpa James) 



Plate LXIV 



Gregarious, yellowish-green, becoming brownish, especially below; branches 

 simple, erect from a branched underground stem; leaves crisped when dry, 

 when wet ascending, lance oblong to oblanceolate, or obovate, up to 8 mm 

 long by 1.2 wide, flat, or but faintly undulate, acute, marginally spinulose- 

 serrate in upper half, bordered from near base to tip with colored, incrassate, 

 narrowly linear cells, 2 or 3 cells wide and usually 2 cells thick; costa strong, 

 percurrent (or excurrent), about 1/10 the width of the leaf, with rarely one 

 or two teeth dorsally near the apex, frequently with from one to three lamella 

 on upper side of costa in upper part of leaf, the lamellae smooth and usually 

 2-3 cells high; leaf-cells smooth, the basal thin-walled and semi-inflated, 

 rounded-oblong to rectangular, 1-4:1, the marginal much narrower, above base 

 the cells become incrassate, rounded to quadrate-hexagonal. Not seen in 



