i 9 1 2] - JONES— DIANTHERA 3 



As Holm (5) has pointed out, both the vertical aerial stem and 

 the horizontal submerged rhizome show, in a cross-section of an 

 internode, six peripheral and one central bundle, each of leptome, 

 hadrome, and pith, and each completely surrounded by a thin- 

 walled endodermis, each having, therefore, the appearance of a 

 complete stele (fig. 8). For this reason, Holm says that the plant 

 is polys telic; from its development, however, it will be seen that 



it is really astelic. 



At each node there is a fusion of the six peripheral meristeles to 

 form a complete ring of vascular tissue, which breaks up in a very 

 regular way to form the six peripheral meristeles of the internode 

 above (fig. i). Each of the bundles of the lower internode divides 

 at the node to form a Y ; then each branch fuses with a branch of 

 the adjacent Y, thus giving rise to the six peripheral bundles of the 

 next internode. The single leaf traces join the vascular system of 

 the stem at the crotches of two opposite Y's. The two bundles 

 which supply the traces are usually, though not always, larger than 

 the other four. There is also a connection made, at each node, 

 between the central bundle and the peripheral ring of vascular 

 tissue by means of a transverse arm, coming out from the central 

 bundle at right angles to it and fusing with the vascular ring just 

 below the insertion of the leaf traces (figs. 3-8 show a series of 

 transverse sections through the node). The structure of the node 

 next above or next below the one described is exactly the same, 

 except that its plane of symmetry is at right angles to that of the 

 adjacent one, as is shown in fig. 1. A diagram of the path of 

 the bundles in a mature plant is shown in fig. 2. 



The seeds 



The seeds (figs. 11 and 12) are much flattened, and are nearly 

 circular in outline. They are about 2-3 mm. in diameter, and 

 about 0.75-1 mm. in thickness. On the lower side the edge of 

 the seed is slightly hollowed out to form a pocket in which lie the 

 hilum and the micropyle. The testa is brown in color, and has a 

 much roughened surface, owing to the distortion of the underlying 

 cells, of which there are two to four layers (fig. 10). The walls of 

 the epidermal cells are thickened in bands which fuse at some 

 places, and at others taper to a point and disappear. The inner 



