JUNGERMANNIACE^. ( SCALE-MOSSES.) 717 



20. PLAGIOCHILA, Dumort. (Fl. 24.) 



Leaves large, succuhous, rounded or truncate above, dentate or spinose or 

 rarely entire, the dorsal margin reflexed ; uuderleaves usually none. Dioecious 

 or monoecious. Fruit terminal, or axillary by the growth of offshoots. Invo- 

 lucral leaves larger than the cauline ; perianth laterally compressed, erect or 

 decurved, obliquely truncate and bilabiate, the lobes entire or ciliate-dentate. 

 Capsule thick, oval. Elaters attached to the middle of the valves. Autheridia 

 oval, 2 - 3 in the axils of spicate leaves. ( Name from Tr\dyios, oblique, and xe^Aos, 

 'ip, from the form of the perianth.) 



* Underleaves 2 -3-cleft, fugacious. 



1. P. porelloides, Lindenb. Branches ascending ; leaves subimbricate, 

 convex-gibbous, rouud-obovate, the uppermost repand-denticulate, the rest en- 

 tire, the dorsal margin reflexed ; perianth terminal, oblong-ovate, the mouth 

 compressed, denticulate. — Among mosses in swamps and river-bottoms ; 

 common. 



2. P. interrupta, Dumort. (PI. 24.) Prostrate, horizontally branched, 

 copiously rooting; leaves imbricate, horizontal, oval, entire or slightly repand ; 

 underleaves lanceolate ; perianth terminal, broadly obconic, the mouth com- 

 pressed, repand-crenulate. (P. macrostoma, Sulliv.) — Moist banks and de- 

 cayed logs, N. Eng., Ohio, and northward. (Eu.) 



* * Underleaves wanting. 



3. P. spinulosa, Dumort. Creeping, branches ascending; leaves re- 

 mote, obliquely spreading, obovate-cuueate, the dorsal margin reflexed, entire, 

 the ventral and apex spinulose-toothed ; perianth rounded, at length oblong, 

 the mouth spinulose. — Shaded rocks in mountain regions ; rare. (Eu.) 



4. P. asplenoides, Dumort. Branched, creeping or ascending ; leaves 

 subimbricate, obliquely spreading, round-obovate, entire or denticulate, the 

 dorsal margin reflexed ; perianth much exceeding the involucral leaves, ob- 

 long, dilated at the truncate or ciliate apex. — In rockv rivulets ; common. 

 (Eu.) 



21. MYLIA, S.F.Gray. (PI. 25.) 

 Leaves succubous, semi-vertical, circular, or ovate and pointed ; underleaves 

 subulate. Dioecious. Fruit terminal or pseudaxillary. Involucral leaves 2, 

 clasping ; perianth ovate-oblong, laterally compressed above a subterete base, 

 the apex at length bilabiate, denticulate. Capsule ovate, coriaceous. Elaters 

 free. Antheridia 2 in the axils of bracts clustered near the apex of distinct 

 branches. (Name from Mylius, an early botanist.) 



1. M. Taylori, S. F. Gray. Stemserect, nearly simple, radiculose; leaves 

 large, convex, orbicular, entire, purplish ; cells large ; underleaves lance-subu- 

 late, entire or subdentate ; perianth terminal, oval ; calyptra finally long- 

 exserted. (Jungermannia Taylori, Hook.) — Wet rocks, high mountains of 

 N. Eng. and N. Y. (Eu.) ' 



22. HARP ANT HITS, Nees. (PI. 23.) 

 Leaves succubous, semi-vertical, ovate, emarginate ; underleaves connate 

 with the leaves, ovate or lanceolate, 1 -toothed at base Dianious. Fruit on 

 short shoots from the axils of the uuderleaves, finallv sublateral. Involucra) 



