448 T. Holm — Studies in the Cyperacece. 



Tannin was found in both the bark and pith. The same reduc- 

 tion in the size of the pith was, also, observed in F. laxa and 

 F. autuninalis ; in the latter the stereome appeared to have 

 become more developed than in the stem, forming larger- 

 groups and, also, by being more thick-walled. 



The root. 



With the exception of Tan Tieghem,* Russow, De Bary 

 and Klinge, very few authors have given account of the root- 

 structure in the Cyperacece. The elaborate work of Klinge, 

 to which we have often referred in our articles upon this order, 

 contains a number of detailed descriptions, by which we are 

 enabled to obtain a broad view of 'the general structure besides 

 a comparison between the principal characteristics of the roots 

 in Cyperacem and Graminece. The very important character 

 to which Klinge has called attention as one of the most reliable 

 for distinguishing roots of Cyperacece from Graminece, the 

 tangential collapsing of the bark-cells, this character has, also, 

 been observed by the writer in a number of genera from this 

 country, including Fimbristylis. The structure of the endo- 

 dermis seems, according to our own observations, to represent 

 a number of variations. This sheath occurs in our species of 

 Fimbristylis with more or less thickened cell-walls ; in F. cas- 

 tanea the thickening appears to have reached the maximum, 

 and the individual cells look as if their lumen had almost 

 entirely disappeared. In /. thermalis and F. stenophylla the 

 endodermis is, also, distinctly thick-walled with a number of 

 layers representing an O -endodermis. And in F. autumnalis, 

 which shows a rather weak mechanical structure, the endo- 

 dermis is, nevertheless, somewhat thickened, sufficiently to be 

 characterized as an O-endodermis. In F. laxa the endodermis- 

 cells are not thickened all round, but only on the radial and 

 inner walls in the shape of a typical IJ-endodermis. 



In regard to the pericambium, we have only noticed this 

 tissue as consisting of a single layer of thin-walled cells, or as 

 in F. oastanea of thick-walled. Otherwise the pericambium 

 shows the same peculiarity, discussed in the works cited above, 

 by Klinge and Van Tieghem : that it does not form a closed 

 ring in all the Graminece and Cyperacece, but is freo t uently 

 interrupted by the protohadrome. It will, however, require 

 further observation in order to ascertain, whether this fact is 

 common to all or only to certain genera of the Cyperacece. 

 While Klinge has observed the protohadrome to border 

 immediately on the endodermis, thus breaking through the 



* Van Tieghem, Ph., Recherches sur la symetrie de structure des plantes vascu- 

 laires (Annales d. sc. nat., 5th series, vol. xiii, Paris, 1870-71, p 5). 



