T. Holm — Studies in the Cyperaceoz. 23 



species may be distinguished, although their morphological 

 characters are so prominent as to leave the anatomical dis- 

 tinction unnecessary. But it is, nevertheless, quite interesting 

 to compare their structure in order to ascertain whether there 

 may be some connection between the structure of their tissues 

 and the character of the climate and soil wherein they grow. 

 Fuirena scirpoidea Las several features in common with some 

 of the most pronounced desert-plants, viz : the reduction of the 

 leaf-blades in contrast to the other species of the genus. It 

 grows in dry, sanely soil and is a very common plant in sub- 

 tropical Florida. The anatomy of its almost leafless stem 

 shows us a well differentiated palissade-tissue in the bark, thus 

 the stem has taken the function of the leaf ; the very thick- 

 walled epidermis is another character by which F. scirpoidea 

 approaches itself to the desert plants, e. g., Panicum turgi- 

 dwn, as described in Yolkens' excellent work upon desert- 

 vegetation (1. c). We must not, however, consider our 

 Fuirena as an exception from most of the Cyperacece because 

 its leaf-blades are not developed ; this very same external 

 structure is, as we remember, very common in species of 

 Scirpus, Eleocharis and in many Juncacew. But these almost 

 leafless species grow always in wet soil, in marshes, etc., while 

 our Fuirena prefers the dry sand, although not entering in the 

 "Scrub" vegetation, which to a certain extent constitutes a 

 desert-vegetation in Florida. 



The anatomical characters are, otherwise, to be observed in 

 the root, viz : the peculiar endodermis in F. scirpoidea, the 

 lacunes in the bark in F. squarrosa, while the leaf shows us a 

 dense hairy covering and very prominent stomata in F. squar- 

 rosa in contrast to F. seirpoidea • the stem of F. scirpoidea 

 with its firm structure and the bark developed as palissade- 

 tissue is very different from the weak stem of F. squarrosa 

 with its large lacunes. 



Washington, D. C, January, 1897. 



Bibliography. 



1. Baillon, H. Monographie des Cyperacees, Restiacees et 

 Eriocaulacees. Paris, 1893, p. 361. 



2. Didrichsen, F. Afbildninger til Oplysning af Grseskimens 



Morphologi, edit, by Warming. Botan. Tidsskr., vol. xviii, 

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3. Duval-Jouve, I. Sur les feuilles et les noeuds de quelques 



Graminees. Bull. soc. bot. de France, vol. xvi, Paris, 1869, 

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