THE BRYOLOGIST 



Vol. XV JANUARY 1912 No. 1 



NOTES ON NORTH AMERICAN SPHAGNUM, II 



A. LeROY ANDREM^S, Ph. D. 



THE SUBGENUS INOPHLOEA R US SOW 



Members of this group can readily be recognized as such in the 

 field ; if the large size and general aspect of the plants leave any 

 doubt, it may readily be dispelled by examination under a hand-lens, 

 as the cucullate leaf apices are unmistakable. Its species them- 

 selves are on the other hand most difficult to distinguish from each 

 other without microscopical investigation, and show even then very 

 close relationship. Long acquaintance in the field may lead one to 

 suspect the specific identity of a newly found tuft of plants, or in 

 some cases to be certain of it, but the group remains the hardest of 

 all 10 collect with discrimination. 



The stem leaves of all species of this group show the membrane 

 of the hyaline cells almost completely or very largely resorbed on the" 

 outer surface. This matter of membrane resorption, studied most 

 thoroughly by Russow, is to my mind one whose importance has not 

 been adequately recognized in the systematic treatment of the genus. 

 It occurs especially in the stem leaves, in some species also in the 

 perichaetial leaves, sometimes on the one surface, sometimes on the 

 other, sometimes on both. For its observation the leaf may be 

 stained, but with good light and no condenser staining is superfluous. 

 The membrane appears lacking in large gaps of more or less irregu- 

 lar form, but never with ragged outline, leaving often but a narrow 

 border of membrane along the outer edge of the hyaline cell like a 

 coating of ice about the edge of a pool ; sometimes this is restricted 

 to the two ends of the cell, or it may be so completely resorbed that 

 no perceptible trace remains, in which last case one may easily fail 

 to notice the lack of membrane. Ones observation of the surface 

 should be tested by transverse section, which leaves the condition 

 unmistakable. A number of thin sections of the stem are sure to 

 give some sections of stem leaves that can be used. 



With reference to the structure of the perichaetial leaves already 

 referred to, the statement of Warnstorf s descriptions that the basal 

 and central portion is composed exclusively of chlorophyll cells is 

 misleading in that one is likely to interpret it as referring to cells 

 quite of the nature of the chlorophyll cells of the normal leaf struc- 

 ture, which is far from being the case. A transverse section of these 



The November Bryologist was issued November 17, 1911. 



