32 CLADIUM. [class II. ORDER I. 



simple and slender tube, it will suddenly but almost imperceptibly 

 collapse. The root will then incline a little to one side, and an irregu- 

 lar, jerking, rotatory motion, from south-east to north, will commence. 

 With slight interruptions, this motion will continue until the root is 

 completely twisted, and in appearance not unlike an exceedingly deli- 

 cate thread of silk. For some time before and after the circular motion 

 has subsided, it will evince a convulsive, tremulous emotion, like the 

 vvrithings of an insect suffering from acute pain. But if the plant be 

 again carefully placed in water, with its root downwards, the same 

 number of revolutions will be performed in a contrary direction to the 

 first, and when fully untwined, it will assume its original form, appa- 

 rently without injury. 



GENUS X. CLA'DIUM. Twig-rmh. 



Nat. Ord. Cypera'cejE. 



Gen. Char. Perianth single, glumaceous. Glumes concave, of one 

 piece, single-flowered; outer ones smaller, mostly barren. Fruit a 

 nut, which has three slight angles, covered with a loose coat, and 

 destitute of bristles (setce) at the base. — Named from nXaJo;, 

 (ramus,) a branch, or twig; probably on account of the many- 

 branched panicle. 



1 . C. Maris' cus, (Fig. 44.) prickly Tivig-rush. Panicle erect, many 

 times divided, and leafy, spikelets capitate, stem round, smooth, 

 leafy, the margins and keel of the leaves finely serrated. 



English Botany, t. 950. — English Flora, vol. i. p. 36. — Lindley, Sy- 

 nopsis, p. 281. — Hooker, British Flora, vol. i. p. 14. 



Root strong and fleshy. Stem three to five feet high, erect, smooth, 

 round, becoming angular at the top, leafy, joiiits polished. Leaves as 

 long as the stem, striated, tapering to the extremity, the margins and 

 keel cartilaginous, finely serrated with sharp almost prickly teeth. 

 Panicle with from two to six pairs of repeatedly divided, angular, and 

 bracteated branches, each bearing a cluster of from six to eight ovate 

 spikelets, each of which is composed of six or eight light-brown ovate 

 glumes, the inner ones the longest. External coat of the nut large, 

 brown, and shining. Sta7nc7is longer than the glume. Sti/le as long 

 as the stamens, capillary, deciduous. Stigmas two or four. 



Habitat. — In fens and boggy places, but not common. Lake, near 

 Rosthem Mere, Cheshire, — Mr. Campbell. In Norfolk, Kent, Cam- 

 bridge, &c. Very rare in Scotlaiul. 



Perennial ; flowering from July to August. 



