182 T. Holm — Studies in the Cyperacece. 



If we finally compare these anatomical characters with those 

 which Eikli observed in Z. argentea, we will notice a few diverg- 

 encies. This author states, for instance, that the leaf possesses 

 one mediane and numerous lateral groups of bulliform cells, 

 while the leaves we examined showed only one, above the mid- 

 rib (fig. 4) ; besides that the lateral parts of the blade were 

 covered by several layers of large-celled epidermis. Further- 

 more is stated that the leptome and hadrome are separated 

 from each other by a zone of thick-walled cells (mestome-par- 

 enchyma), which we did not notice in any of the species exam- 

 ined. It seems as if the leaf, which Rikli described, may not 

 have belonged to Z. argentea, and perhaps not to Zipoearpha 

 at all. It is, also, to be pointed out that not all of the Cype- 

 racece, in which a chlorophyll-sheath is developed, have a 

 scarcity of stereome, since this tissue is well represented in the 

 species of Zipoearpha. 



Brookland, D. C, October, 1898. 



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