256 THE JOURNAL OF INDIAN BOTANY. 



The leaf-stalk is dorsiventral in its organisation, markedly so in 

 its upper part where it has a distinct groove on its adaxial side. The 

 number of vascular bundles varies from nine to eleven, those nearest 

 the groove being the smallest. (Fig. 3) 



The basal part of the tendril is radial in section, the number of 

 bundles various from sis at the lower to ten in the upper part, and 

 they are as a rule arranged in one ring. There is absolutely no trace 

 of a ventral groove as is present in the petiole. (Fig. 4) 



Both the branches of the tendril show a dorsiventral structure 

 with a distinct groove on the apparently upper surface. The vascular 

 bundles are five in number in the form of an arc open above as seen 

 in a transverse section. (Fig. 5) 



The vascular connections at the node are as follows : — The traces 

 from the tendril, the vegetative bud and the flower-stalk all pass 

 through the cortex and join the bundles of the inner ring. The leaf- 

 stalk sends three traces into the cortex. Of these, one (median) passes 

 down the internode below without anastomosing with any bundle at 

 the node ; the two lateral traces join the two adjacent bundles of the 

 outer ring, each with the one on its own side. One bundle of the 

 inner ring, while coming from the upper internode, gradually decreases 

 in size and ultimately ends blindly immediately above the node or 

 just reaches it. The bundles of the inner ring anastomose at the node 

 and this ring receives a bundle from the outer ring also to take the 

 place of the one that has just ceased at each node. Thus at every 

 node one bundle of the inner ring stops and a bundle from the outer 

 ring joins the inner ring to take its place 1 while the place of the latter 

 is taken by the median leaf-trace which passes down the lower inter- 

 node without anastomosing. The gradual decrease in size of one of 

 the bundles of the inner ring at each internode, as described above, is 

 the cause of the dorsiventrality of the arrangement of the vascular 

 bundles common in the family. (3) 



It is clear from the above description that the bundles of the 

 outer ring are really continuations of the leaf-traces, while the bundles 

 of the inner ring are mainly cauline. 



Lagenaria vulgaris, 



The organs at the node beginning from the left are, a branched 

 tendril with five arms very close to each other, a bud and a flower. 

 The glandular organ is missing. 



The vascular structure of the stem and the leaf-stalk is in general 

 the same as in Benincasa cerifera. 



1 This now inner bundle is not, however, a direct continuation of the outer 

 bundle. 



