T. Holm — Studies in the Cyperacece. 449 



pericambium, in several species of Carex, Eriopharum, Scirpus, 

 Heleocharis and according to Duval- Jon ve, also in Cyperus 

 globosus, Cfuscus^ C vegetus and C. serotinus, Yan Tieghem 

 did not observe this to take place in Carex hrizoides. More- 

 over both Duval-Jouve and Klinge observed a similar separa- 

 tion of the protohadrorae from the endodermis in various 

 species of Cyperus and Gcdilea mueronata. In Carex Fraseri, 

 as we have mentioned in a previous article, the protohadrome 

 is, also, separated from the endodermis. The innermost part 

 of the central-cylinder is in F. autumnalis, F. laxa and F. 

 thermalis occupied by a single, large vessel, and several in F. 

 castanea and F. stenophylla. The conjunctive tissue seems 

 most often to be thin-walled, with the exception of F. castanea 

 and F. laxa. The structure of the roots in our species of the 

 genus does not seem to present any other mechanical protec- 

 tion than that rendered by the thick- walled endodermis, 

 although we should have expected to find a similar protection 

 in the innermost layers of the bark corresponding to what we 

 observed in Scleria and Lipoearpha with their thick-walled 

 bark-parenchyma. 



These anatomical details, which we have observed in North 

 American species of Fimhristylis, seem to illustrate that we 

 have only one genus before us ; the species which by Torrey 

 were referred to Isolepis appear to be inseparable from the 

 others, not only from an anatomical, but, also, from a morpho- 

 logical viewpoint. And if we consider the various species, as 

 we have studied them in this country, they exhibit a sufficient 

 number of characters which may be regarded as " mutual 

 affinities," such as these are understood in orders as large as the 

 Cyperacece. But it does not seem possible to draw any such 

 distinction, as for instance to separate the species into " Xero- 

 phytes or Hydrophytes," even if the local environment might 

 suggest these plants to belong to different " plant-societies." 

 Because the internal structure of the stem, the leaf and the 

 root does not furnish any evidence that certain anatomical 

 features are necessarily dependent on a special climate or soil, 

 neither very dry nor very damp. It seems much more natural 

 simply to acknowledge that such and such species live under 

 such and such conditions, even if we, on the other hand, are 

 unable to account for the similarities and diversities in struc- 

 ture. The statement that bog-plants may possess xero phytic 

 characters and vice versa gives no satisfaction, and is even mis- 

 leading; characters may have been simply inherited without 

 being at present of any particular advantage to the species. 

 The inner, chlorophyll-bearing sheath may represent a char- 

 acter of that kind, its function being, so far, unexplainable. 



