246 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



Acute or short apiculate, alar cells few, large . H. palustre, 398. 

 Obtuse, entire, alar cells hyaline . . H. cnspidatnm, 403. 



2. Alar cells scarcely different or quadrate or rectangular, not 

 abruptly enlarged. 



* Leaves thin, glossy, open; plants mostly small, prostrate or with 

 ascending branches. 



Leaves squarrose, acuminate. 



Sub-serrulate all around, lid apiculate . . H. hispidulum, 378. 

 Entire except the acumen, lid obtuse H. Macounii, 539. 



Leaves loosely imbricate, obtuse or acute. 

 Serrulate, at least above. 

 Nearly as broad as long, obtuse or apiculate. 



Alar cells small, not forming distinct auricles, 



others 1 : 8-10 H. molle, 399. 



Alar cells large, forming distinct auricles, others 



much longer than preceding . . H. dilatatum, 1 601. 

 Nearly twice as long as broad, acute, point often half 



twisted H. alpestre, 399. 



Entire. 



Leaves close set, ovate (1:2). . . . H. Norvegicum, 581. 

 Leaves more distant, rotund .... H. Goulardi, 585. 



* * Leaves firm; plants very large, mostly 1-2 pinnate, erect 



or ascending. 

 Paraphyllia none. 



Capsule smooth when dry. 

 Leaves obtuse. 



Olive or grayish green, 1-2-pinnate, leaves open H. Schreberi, 404. 

 Dirty green to dark brown, almost simple, leaves 



closely appressed H. trifarium, 405. 



Leaves abruptly apiculate, plants pale green . . H. purum, 594. 

 Capsule plicate when dry, plants dark green to reddish 



brown H. scorpioides, 2 406. 



Capsule unknown; plants dark yellow and greenish, branches 



julaceous, few, fastigiate, leaves short apiculate H. turgescens, 406. 

 Paraphyllia present H. Alaskanum, 405. 



1 H. circulifolium C. M. & Kindb., Appendix, no. 583, belonging to this division and de- 

 scribed from sterile specimens, is related to H. dilatatum Wils. 

 8 See Appendix, no. 599. 



