6 ME. C. B. CLABZE OS INDIAN SPECIES OF CYPERTJS. 



very slender tough black roots ; while the species that actually 

 float in tanks (C. cephalotes, G. platystylis) have very thick roots. 

 The woolly-rooted species are confined to Arabia and the neigh- 

 bouring desert countries, and assist probably in collecting water, 

 or perhaps give a better hold on the sand. 



(2) The Culm. 



The culm is erect, never branched until the umbel, and 0-1 

 metre (a very few species attaining 1-2 metres) high. It is naked 

 except for T V~4 its length near the base, where it is sheathed by 

 the bases of the leaves ; in a few species, especially in G. Mundtii 

 and 0. distichopJiyllus, the culm is enveloped half its length by 

 the leaf-sheaths, as also sometimes in G. Eragrostis. Great 

 variation in the length of the culm (accompanied by varia- 

 tion in the development of the umbel) occurs in many spe- 

 cies, and depauperated examples are common. 0. Eragrostis, 

 Vahl, as collected by Schrenk at Lake Alakul (called G. jlaves- 

 cens, /3. rubromarginatus, Schrenk) is only 2-3 centim. high, each 

 culm bearing 1-3 spikelets only : a stunted (not depauperated) 

 form of C. compressus is not uncommon in which the culms are 

 1 centim., the umbel contracted but of numerous large spikelets. 

 C. latispicatus, Boeck., is very variable in this respect ; and I have 

 collected (in Khasia) a form of this absolutely culmless, the well- 

 developed umbel being exactly radical. The culm is generally 

 much longer than the umbel-rays ; but G. radians, Nees et 

 Meyer, and G. Griffitltii, Steudel, are at once distinguished by 

 having the umbel-rays 2-3 (or more) times as long as the culm. 

 The stoutness of the culm ranges from 1-2 centim. down to 

 1-2 millim. in diam. ; yet it is a much more useful character than 

 the length, each species varying in this respect between evident 

 (though troublesome-to-define) limits. Indeed the stoutness of 

 the culm is one of the main characteristics, both with Kunth and 

 with Boeckeler, for forming natural subsections of the species. 

 The group Exaltati (including Papyri) is eminently natural, as 

 also the slender-culmed Aristati. The stout character of the 

 culm is maintained in very short-cuimed examples of Exaltati, 

 and the slender character of the culm in very long-culmed 

 examples of Aristati. 



The culm is trigonous ; but in some species this character is 

 modified until the culm appears perfectly terete ; in others it is 



