34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



BRACHYTHECIACEAE 



PLEUROPUS BONPLANDII (Hook.) Broth, in E. & P. Nat. Planzenfam. i': 



1 136. 1908 



Lcskea Bonplandii Hook, in Kunth Syn. PI. Aequin. i: 61. 1822-28. 



Puebla: Esperanza (4745, 4754). Valle de Mexico {Bro. Ama- 

 hle) : Desierto (1438); Santa Rosa (1504). Hidalgo: El Chico 

 (1580). 



BRACHYTHECIUM 



I must confess that the study of the Mexican specimens belonging 

 to the genus Brachythccimn has been an extremely laborious task : 

 The sterility of many of them on the one hand and, on the other, 

 the difficulty if not the impossibility of obtaining, for the sake of com- 

 parison, good and complete specimens of the types, are among the 

 more important contributory causes. 



I studied nearly 60 numbered specimens and drew almost all of 

 them. They belong, excepting five or six, to the sections Acuminata 

 and Salebrosa. Now except for B. salehrosum (HofTm.) and B. lo.vi- 

 rcticiilatum Card., the Mexican species of this group are very diffi- 

 cult to identify. Eor one specimen that agrees with the type there are 

 many others which combine characters common to several species and 

 which one hesitates to attribute to one rather than the other. Hence 

 I gave three different names in succession to the same specimen with- 

 out being entirely satisfied with any of them. My conclusions are as 

 follows : 



( 1 ) Several of my determinations remain uncertain ; they are 

 merely probable. 



(2) Some of the Mexican species are very polymorphous, like 

 our B. rutabulum, and their forms have been taken for new species. 

 Therefore one must not be surprised to find indeterminable specimens 

 which in turn seem like new species. 



It will be a task for future bryologists, those who will have the 

 privilege of studying the flora in situ, to weigh these variable species 

 and to make, with a thorough knowledge of the facts, whatever re- 

 ductions are necessary. 



BRACHYTHECIUM TENUINERVE Card. Rev. Bryol. 37: 65. 1910 



Puebla: Xuehitl, near Esperanza (7988). A form which by its 

 laxer areolation marks a tendency toward B. lanceolifolium Card. 



Valle de Mexico (Bro. Amahlc) : Contreras (1221, 1483); De- 

 sierto (1618) ; Salazar (1717); Llano Grande (1738). This is a 

 form with very elongate branches. 



