May, 1906.] Key to Liverworts. 535 



12. Plant green to reddish brown; leaves on the same stem hardly 



equal to each other in shape, often bearing red globules on the 

 lobes of the upper leaves; perianth whitish, alpestris Schleich. 

 Plant green to reddish green; leaves on the same stem similar in 

 shape, often bearing vellowish globules on their lobes; peri- 

 anth green to reddish. ventricosa Dicks. 



13. Involucral leaves like the cauline; leaves roundish-ovate, 2-lobed 



with obtuse sinus and inequilateral, obtuse lobes; perianth 



long-oval to pyriform. inflata Huds. 



Involucral leaves unlike the cauline; leaves 2-6-cleft or-lobed. 14. 



14. Usually purplish-black; leaves imbricate or distant on erect fer- 



tile stems with obtuse, Avavy lobes; involucral leaves cristate- 

 undulate, obtusely many-lobed; perianth long-clavate. 



laxa Lindb. 

 Light to blackish and purplish-green; leaves horizontal or semi- 

 vertical with acute or obtuse lobes; involucral leaves 3-5 cleft 

 or lobed. 15. 



15. Plant small (about 2 mm.), light green often with a purplish hue; 



leaves semivertical, erect-spreading; upper involucral leaves 

 longer than wide; perianth oblong, pale, often banded and 

 spotted with pink. cxcisa Dicks. 



Plant large (5-15 mm.), deep to bluish green; leaves horizontal, 

 closely imbricate, the upper wavy-crispate ; involucral leaves 

 wider than long; perianth oval, whitish green. 



cxcisa Dicks, var. crispa Hook. 



16. Underleaves none; leaves of irregular shape, 3-or more lobed with 



obtuse sinus and numerovis, wide or narrow, always very 

 acute, dentate lobes, thus giving the plant a crispate appear- 

 ance, incisa Schrad. 

 Underleaves present, sometimes obsolete. 17. 



17. Leaves divided to 73 into 3 or 4 acute lobes and coarsely reflexed— 



dentate at their base; underleaves numerous, deeply bifid 



with ciliate-dentate base. setijormis Ehrh. 



Leaves divided to J^ into acute or obtuse lobes and not dentate 



at base; underleaves entire or 2-toothed or often obsolete. 18. 



18. Stem often with many vertical shoots, bearing loosely imbricate 



leaves; perianth oblong. attennata Martins. 



Stem without shoots; perianth ovate. barbata Schreb. 



Kantia S. F. Gray. 



Without ventral runners; underleaves bifid, lobes short oval-tri- 

 angular, acute or obtuse. Trichomanis S. F. Gray. 

 With ventral runners; underleaves minute, the upper orbicular, 

 bifid, the lower twice 2-lobed, the primary lobes round-quad- 

 rate, the secondary ovate or subulate Snllivantii Underwood. 

 Lejeunia Libert. 



1. Underleaves entire. clypcata Sulliv. 

 Underleaves bifid or obsolete. 2. 



2. Underleaves bifid. 3. 



LTnderleaves obsolete; leaves muriculate-denticulate. 



calcarea Libert. 



3. Monoecious; stem long, somewhat branching; leaves roundish- 



ovate, obtuse; perianth obovate-clavate. 



scrpyllijolia Libert, var. americana Lindb. 



Dioecious; stem filiform, pinnately branching; leaves ovate-tri- 

 angular, rounded or obtuse; perianth broadly pyriform, 

 5-carinate. Plant minute. htccns Tayl. 



Lcpidozia Dumort. 



Leaves decurved, 3-4 cleft, the lobes lanceolate, formed by more 

 than 2 rows of cells. reptans Dumort. 



Leaves incurved, ^2-3 cleft or parted, the lobes subulate, formed 

 by 2 rows of cells. sctacea Mitt. 



