ME. C. B. CLABKE ON INDIAN SPECIES OF CTPEETJS. 23 



found. In the O. auricomus group the nut is peculiarly umbo- 

 nate ; in the Elegantes group the nut is ellipsoid, acute at both ends 

 sharply trigonous, somewhat large ; in the Conglomerati (and 

 some of the allied Arenarii) the nut is unequal, dorsally com- 

 pressed. So much is this the case that, where great differences 

 in the nut are found in one of our groups, it may be suspected we 

 have not discovered the true affinity. 



The nut is smooth throughout the genus ; an imperfect tuber- 

 culation occurs in C. Haspan (and a few others), but only casually 

 in some specimens, not throughout the species. The colour of 

 the nut is a good character, but the nut is in a great majority 

 dark ; and care of course must be taken not to describe colour 

 from unripe or imperfect nuts, which abound in some species 

 (as C. pygmceus). 



The size of the nut is measured in comparison with the length 

 of the glume ; it is said, therefore, to be " very large " in O. dif- 

 formis (where it is nearly as long as the glume), though, speaking 

 absolutely, it is small. The nut in C. Haspan is very small, in 

 C. Iria large ; and these species, from Linnaeus downwards, are 

 nevertheless mixed in herbaria. 



I find, however, a considerable range of size (not of form) in 

 the nuts of many species. The plant which I call C. exaltatw, 

 Retz., var. Oatesii, is very likely distinguishable as a species ; 

 but as I have been able to hit on no tangible character except 

 the size of the nut (to separate it from C. exaltatm) I leave it as 

 a variety. 



In Cyperus, as in some other genera of Cyperacese, botanists 

 have exhausted their vocabulary in describing the surface of the 

 nut as shining, reticulate, velate, puncticulate, transversely 

 marked, &c. &c, according to the general appearance it presents 

 under a pocket lens, without (as I conceive) getting clear hold 

 of some important differences of structure met with. 



The outermost layer of cells of the nut in Cyperus is without 

 colour, usually hyaline, sometimes opaque, white, permanent or 

 flaking off (detergibiles), not very thick or lax (as often in Iso- 

 lepis), and either subquadrate (figs. 31-39) or oblong longitudi- 

 nally (fig. 40) (2 or 3 times as long as broad). There appears 

 nothing intermediate between these two cases. The only longi- 

 tudinal-celled species of Cyperus are about a dozen, all in Pycreus, 

 and forming a natural group, of which C. flavescens is a well- 

 known example. This character is so absolute that I am able to 



