THE BRYOLOGIST 



Vol. III. Aprii,, 1900. No. 2. 



KEY TO BRYUM. 



BRYUM is one of the most difficult and unsatisfactory genera 

 for beginners, as well as for any one, unless he be a spec- 

 ialist in that particular genus. The key which is here 

 printed will not enable a beginner or any one else to accurately 

 determine Bryums without a careful comparison with a good de- 

 scription. Often authentic specimens will be necessary to make 

 sure of the plant. The key is intended to help the student to lo- 

 cate the species certainly within two or three closely allied species 

 and to give hints as to the exact species. 



The length of costa and distinctness of border vary on the 

 same plant. The border often varies on the same leaf. Lower 

 leaves of Bryum are usually shorter and broader than the upper 

 leaves and always have a shorter costa. The inner comal leaves are 

 usually larger and narrower than the general run of leaves on the 

 plant. The border of a Bryum leaf is usually most distinct near 

 the base and least distinct near the apex. In using the key select 

 leaves in the lower part of the upper third of the leafy portion of 

 the stem and look for border in the upper third of the leaf. The 

 margin of the leaves is frequently strongly recurved and gives 

 the appearance of a margin whether a margin be really present or 

 not To make sure, the margin must be flattened out by manipu- 

 lation with needles and pressure on cover-glass. It may even be 

 necessary to use scissors. 



Some of the species vary in the characters used in the key, 

 hence these species have to be included under each of the head- 

 ings. For instance B. palletis, B. turbinaium and B pseudotri- 

 tjitetruni may have the apex of leaf either serrate or entire, and 

 are included under each division of section 5. In section 17 these 

 three species are referred back to section 14, where they have 

 already been treated. 



Height as used in the key refers to the gametophyte alone; it 

 does not include the capsule and seta. 



The leaves in Bryum are smaller than in Mnium and the leaf 

 cells are markedly longer than broad except in B- capillare, which 



