MR. C. B. CLARKE ON INDIAN SPECIES OF CTPERUS. 7 



intensified, and we have a triquetrous stem. The culm is com- 

 monly nearly round below, becoming trigonous upwards, most 

 sharply so under the umbel. The culm is frequently more or 

 less unequally trigouous, and sometimes excessively so, until it 

 is described as complanate, as occurs in C. Haspan (type) and 

 C. malaccensis. In C. articulatus (aud C. nodosus, scarcely spe- 

 cifically distinct) the culm is terete, quite smooth, continuous 

 when fresh ; but after a day or two iu drying-paper the pith 

 thickens at regular intervals, giving the culms a falsely articulated 

 appearance. This character, not uncommon in Eleocharis and 

 Scirpus, is not distinctly brought out in any other species of 

 Cyperus. 



The degree of sharpness of the angles of the culm is marked in 

 certain species, as in G. turgidulus, in which the culm is 3-winged, 

 and is in specific descriptions usually treated as an important point, 

 but I fear can only be relied on as a subsidiary character. C. 

 tegetiformis, Koxb. (O. enodis, Boeck.), has been separated from C. 

 corymbosus, Kottb. (C. diphyllus, Eetz.), by the more acutely-angled 

 culm (especially close under the umbel) ; but I doubt whether the 

 two forms can be separated by that or by any other character. 

 Many species (both among those with slender and those with 

 moderately thick culms) have the faces between the three angles 

 striate; and these striatums iu some species are strengthened so 

 as to obscure the angles, until we finally get a terete, striated, or 

 fluted culm. Such culms are often accompanied by rigid leaves 

 (with inrolled margins), and are characteristic of dry-country 

 species, as the Conglomerati ot Arabia and mauy species of the 

 Great Thirst-Land in South Africa. 



The culms in Cyperus are generally smooth, or only microsco- 

 pically scabrous on the angles near the top. In C.platyphyllus, 

 Eoem. et Sch., a very large species, the angles of the culm are 

 serrulate, cutting the hand. 



The species of Cyperus are in general quite glabrous ; in a 

 few species there is a pubescence on the rhachis of the spikelets, 

 and in a very few species there are very slender hairs on the leaves. 

 The pubescence only extends to the culm in the following.— 

 in C. viscosus (and one or two allied species) the culm is puberu- 

 lous, or with microscopic papilla) giving it almost a sticky cha- 

 racter; in C. retrofractus, Asa Gray, the culm is manifestly 

 pilose. 



