430 



number of the bundles is indicated by the isolated groups of 

 sieve-tissue. The cambium is no doubt always rudimentary. 

 The endodermis which surrounds the central cylinder is fairly 

 distinct. In the vertical part of the rhizome, on the other 

 hand, the bundles are separated more or less from each other 

 and leave room for the medullary rays, of which the elements 

 are much elongated in a radial direction and are non-lignified. 

 The cambium is capable of division but is fascicular only. In 

 the outer part of the wood large vessels occur in fairly distinct, 

 tangential layers separated by wood-parenchyma, an arrangement 

 which recalls the formation of annual rings. The primary 

 wood has smaller vessels than has the secondary. Secondary 

 cortex is developed only to a slight extent. The pith cells are 

 crowded with starch especially those in the vertical part of the 

 rhizome. 



The peduncle is somewhat furrowed; the epidermis con- 

 sists of small cells, the outer wall, especially, is thick and is 

 provided with a smooth cuticle. The stomala project somewhat 

 (Fig. 58,-/!); the epidermal cells contain a small amount of 

 chlorophyll. The cortex consists of 5 — 6 layers of fairly 

 closely-placed, cylindrical cells with rather thick walls. The 

 bundles number about seven and are closed and have on the 

 outside a fibrous tissue, 3 — 4 layers thick. Upon the inner 

 side of the wood from one to two layers of slightly developed 

 wood-parenchyma occur; between the latter and the vessels, 

 there is, in the larger bundles, some non-lignified parenchyma, 

 and between the large group of sieve-tissue and the vessels 

 some wood-parenchyma. An interfascicular, and in part fairlj 

 strong, mass of ligniQed-parenchyma, about four layers thick, 

 is present; the pith is broken down in places in the fully 

 developed axis. 



Along the larger veins of the upper surface of the leaf 

 there are a few small hairs. The outer walls of the epidermal 

 cells of both the upper and the lower surface are fairly thick, 



