C. A. BARBER 105 



confined, to the basal, thickening portion of the shoot. It is not by any means 

 necessary that runners should be formed only in a horizontal direction ; thev 

 may trend downwards or upwards and, indeed, are not infrequently found 

 in a vertical direction {cf. PI. XXVIII). And in this case they remind one 

 of the long preliminary joint formed in a seedling when it is too deeply planted 

 and is not in a position to tiller freely. It is interesting to note that runners do 

 not usually give rise to branches, and that, in the curved portions, it is usual 

 for only the buds on the outer sides to form shoots, those on the inner sides 

 remaining small or dying early. 



The curvatures occurring at the base of the shoot are usually symmetrical 

 through a number of joints, and both the nodes and internodes take part in it. 

 In fully formed canes this is not possible in the internode because of the hardness 

 of the rind, but at the node there remains throughout the life of the plant 

 a meristematic zone which makes a bend possible. We thus come across 

 bends in the canes long after the curving portion is passed, whereby a shoot is 

 able to assume the erect position and regain it if accidentally thrown down, 

 exactly as in grasses laid by a storm. This bending takes place chiefly in the 

 " growth ring " which is usually greatly increased in w^dth on the underside of 

 the bend. In some varieties this nodal bending is characteristic of all the cane 

 joints, whether it is necessary to alter the position of the cane or not and we 

 accordingly get a zigzag cane with bendings in alternate directions. Zigzag 

 joints usually occur in canes with long joints, and hence they are met with 

 in the Saretha and Pansahi groups, but are absent in the short-jointed Sunnabile 

 and Mungo varieties. 



This arrangement of the branches of the cane is of great importance for 

 its healthy development. Where the branches are too congested, the buds 

 are suppressed and killed along the contact surfaces or, if they survive, they 

 give rise to small, feeble, whiplike branches which are only very rarely able to 

 force their way upwards and form canes. For the demonstration of this phase 

 of the plant's activity, it is advisable to form a ground plan of the shoots, and 

 this is sometimes very instructive. It is frequently possible to separate great 

 sectors of the branching system by merely cutting through successive 6s at 

 their bases. Such separated portions often assume the form of a crescent and 

 can be easily fitted into the other sectors, and an example of this is given in 

 Plate XVII, fig. 8. Some of the schemes thus produced are highly symme- 

 trical in vei-tical section (figs. 6 and 7), and show that the arrangement of the 

 branches of the cane, with reference to the light available, is on a par with the 

 fitting in of the leaves of a plant or the tops of the trees in the great primeval 



