— 28 — 



turning to Correns, I made the plant with much confidence Dicranum montanum; 

 comparison with herbarium specimens confirmed the determination. 



The second case was that of sterile Encalypta contorta. I had determined the 

 plant, but wanted assurance. Correns, page 98, promptly furnished it, pictur- 

 ing the brittle, brown, thread-like, " Brutkoerper" found so abundantly on this 

 plant. 



Corren's notable work will aid students in the determination of many sterile 

 mosses. 



Winona, Minn. 



HYMENOSTOMUM IN NORTH AMERICA 



A. LeRoy Andrews 



1. Delimitation of the genus 



Amongst many uncertainties in a perplexing group of moss forms, one fact 

 is too clear to deserve to be obscured by unjustified taxonomic partitions: namely 

 the close natural relationship of many species which have hitherto usually been 

 divided among the genera Astomum, Hymenostomum and Weisia. As represented 

 in the north temperate zone, where their types belong, practically all of their 

 species show gametophytes with no essential difference and only a series of sporo- 

 phytes representing such a close gradation of forms that not only are the species 

 still debatable, but the genera are in each case connected by forms which can with 

 about equal justice be placed in either genus. This is particularly true in Eu- 

 rope, whose moss-flora has been most intensively studied. The species generally 

 known as Hymenostomum rostellatum (Brid.) Schimp. is as good an Astomum as 

 an Hymenostomum^ and its recent revival as a separate genus Kleioweissia? Bayr- 

 hoffer, 1849, by Loeske^ would make matters worse rather than better. The 

 case is not greatly different with the species of the tropics and the southern hemi- 

 sphere. On what grounds Brotherus^ includes with Hymenostomum as distinct 

 from Astomum the minute species H. ahhreviatum (Thw. & Mitt.) Broth, from 

 Ceylon and H. suhacaule (Mitt.) Broth, from Ecuador^ is not readily evident.^ 

 Before finishing his work he had apparently forgotten having thus disposed of 



iCf. Limpricht in Rabenhorst, Kryptogamenflora, IV, I, 224. 1886. 

 2The above is the original spelling. 



^Studien, 76. 1910. Bayrhoffer, Ubersicht der Moose, Lebermoose und Flechten des Taunus, 

 3. 1849; Bayrhoffer seems to have taken the name from Bryologia Europaea. 

 ^Engler & Prantl, Naturliche Pflanzenfamilien, I, III, 386. 1902. 



^Mitten (Journ, Linn. Soc, Bot., XII, 131. 1869) had recorded it from Bolivia as well as 

 Ecuador. 



^The combination //. suhacaule seems to go back to Paris, Index Bryologicus, 596 (1895), 

 though not so credited by Brotherus. The other combination H. abbreviatum is on the other hand 

 accepted by Paris in his second edition, II, 356 (1904) after he had included the species with Syste- 

 gium i = Astomum) in his first edition, 1258 (1897). The combination Astomum subacaule was 

 made by Jaeger, Musci Cleistocarpi, 13 (1869). 



