18 MB. C. B. CLABKB ON INDIAN SPECIES OF CTPEBUS. 



the same ; but the rhachilla is usually thickened, often almost 

 spongy. In Diclidium the spikelets finally break up into one- 

 seeded joints, nearly in the manner of Rotibcellice among Grasses. 



(7) The Glumes. 



In Gyperus perhaps more attention than is deserved has 

 already been paid to the glumes, more especially to their being 

 mucronate or obtuse, to their colour, and to the greenness of the 

 dorsal nerves. 



As to the mucronatiou, there is no point more illusory, even in 

 the same species and example. The green nerves of the back 

 unite and are just excurrent as a mucro close beneath the apex 

 of the glume, or are not excurrent ; and the two cases fade one 

 into the other, as in the common species G. pwmilus, Linn. (i. e. 

 C. nitens, Yahl), of which the varieties called mutica,patens,trun- 

 catula are without the mucro. The same variety in mucronation 

 occurs in the Conglomerati, and almost throughout the genus ; 

 though in particular species, as in G. rubicundus, Vahl, the mu- 

 cronation appears characteristic. Still more untrustworthy is the 

 mucronation as a sectional character : G. amabilis, Vahl, one of 

 the most characteristic of the Aristati, is often absolutely devoid 

 of aristation ; while G. lucidulus, Klein (correctly placed next G. 

 compressus by Hooker f ., and Hance), has been removed entirely 

 out of its proper place by Boeckeler, apparently solely because its 

 glumes are not acute cuspidate. 



The colour of the glumes is an even more dangerous character to 

 lean upon : it still remains as diagnostic in G. melanostachyus, G. 

 atronitens, &c, and many other species of which (with their allies) 

 we know little ; but in the widely-known G. polystachyus, G. glo- 

 bosus, G. IcBvigatus, &c, colour goes for nothing as a specific cha- 

 racter ; we have, indeed, the whole range of colour from straw- 

 colour to black in the self-same species. There are indeed few 

 species amply illustrated in our herbaria of which the range of 

 colour is not considerable. Nevertheless, in a broad way, a par- 

 ticular tint characterizes most species. G. Jiavescens is nearly 

 always yellowish ; G. dilutus is nearly always a reddish brown, 

 &c. The occurrence in Gyperus of glumes which are 3 -7-nerved, 

 green on the back, yellow, red, purple, &c. on the sides, is so 

 common that the green nerve is hardly worth mention in specific 

 descriptions ; and from accidental circumstances the usually 

 green-backed species sometimes have no green tint. 



