BARNES NOETH AMERICAN MOSSES. 233 



THUIDIUM, p. 321. 



I. Plants small (to 5 cm.), delicate, creeping, 1-% pinnate. 



Costa of stem leaves wide ( leaf base). 



Branches papillate, leaf cells Qju diam. . . T. pygmaeuin, 322. 

 Branches papillate, leaf cells 9/*, longer at margin T. mi nut alum, 322. 

 Costa of stem leaves narrow (^ leaf base). 



Leaf cells with several minute papillae T. scitnm, 1 323. 



Leaf cells with one papilla (rarely two). 



Branch leaves roundish ovate, short acuminate T. Yirginianum, 8 324. 

 Branch leaves ovate lanceolate, long acuminate T. microphyllum, 8 324. 



II. Plants larger (to 10 cm.), creeping, 1-3 pinnate, forming exten- 

 sive flat mats. (Ill) 



Perichaetial leaves ciliate, costa of stem leaves not reach- 

 ing point T. delicatulnni, 325. 



Perichaetial leaves not ciliate. 



Costa of stem leaves filling point T. recognitum, 325. 



Costa of stem leaves % length . . . . T. Philiberti, 443a. 



[T. pa Judos tun may be sought here.] 



III. Plants large (to 10 cm.), erect or ascending, 1-pinnate, in 



wide tufts. 

 Leaf cells roundish or oblong (1 : 1-2), strongly papillose 



both sides . T. abietinuin, 326. 



Leaf cells long rhombic to linear (1 : 3-6), smooth above. 

 Stem leaves soft, sub-clasping, decurrent . . T. Blandoyii, 326. 

 Stem leaves rigid, plicate-striate, sub-decurrent T. palmlosum, 4 330. 



This genus has been revised by G. N. Best, Bull. Torr. Bot. Club 23: 

 78-90. 1896, and we have been able to avail ourselves of his suggestions 

 by recalling MS. T. tamariscinum Hedw. and T. remotifolium Grev. 

 are not N. American; T. erectum Duby = T. delicatulum L.; If. calyp- 

 tratum Sull. = T. microphyllum (Sw.) Best, an earlier name for H.gra- 

 cile B. & S., and to it T. lignicola Kindb. is referred as a variety; T. Al- 

 leni Aust. is probably a sterile form of T. delicatulum L. 



1 See Appendix, no. 441. Not recognized by Best. 



2 T. Virginianum (Brid.) Lindb. = Hypnum gradle Lancastriense S. & L., L. J. 

 Man. 324. 



8 T. microphyllum (Sw.) Best = Hypnum gradle B. & S., L. & J. Man. 324. See also 

 Appendix, no. 442. 



4 T. paludosum (Sull.) Rau & Hervey = Hypnum paludosum Sull.. L. & J. Man. 330. 

 See also Appendix, no. 443. 



