i 9 1 2] JONES— DI ANT HERA 19 



internode, lying between two normal ones, showed three medullary 

 bundles, the central one like the one ordinarily found, one a col- 

 lateral bundle surrounded by an endodermis in structure therefore 

 like one of the peripheral meristeles. The third, also surrounded 

 by an endodermis, was a strictly concentric bundle, with no paren- 

 chymatous tissue, the protoxylem in the center, surrounded by a 

 complete ring of xylem, cambium, and phloem. 



The anastomosing of the bundles in the mature plant has 



been described (fig. 1). 



minute 



similar to that 



the seedling. 



there is more of the 



oriented vascular tissue. Some of the vascular elements on the 

 sides of all six of the peripheral bundles may pass around to the 

 inner face just before entering the node, and so become inverted. 

 Holm, in speaking of the node, says (5, p. 323) "from the union 

 of these steles each of the two opposite leaves receives three mestome 

 cylinders, readilv observed in the Detiole as one central, very broad, 



From the anastomosing bundles 



much smaller 



trace to each of the leaves. This single trace, however, while 

 passing through the cortex, gives off a branch on each side, so that 

 each petiole does receive the three bundles as described by Holm. 

 This giving off of a single leaf trace, which trifurcates while yet in 



found in all of the Acanthaceae. 



Tieghem (11), the conformation 

 It should be noted, however, that 



DeBary (3, p. 243), in speaking of the course of the bundles in the 

 stem, places Ruellia maculata in the group described as having "leaves 

 opposite: traces of three or four bundles, which unite at the second 



not pectinated." 

 been fully described 



seedling 



with 



by Holm. In structure they are identical with 



nence the correction concerning the presence of the marginal strand 



of collenchyma in the blade has to be made here 



The axillary buds of the mature plant 



As in the seedling, a bud is usually formed in the axil of each 

 leaf. Those at the base of the aerial shoot usually develop into 

 rhizomes, or more rarely into vertical aerial branches. In either 



