— 274 - 



especially pure bast bundles that are also to be found directly 

 under the epidermis and facing most of the radial walls between 

 the outer circle of lacunae. Between the epidermis and the outer 

 circle of lacunae there is one layer of cells. The endodermis is 

 decided G-endodermis. The axial cylinder is comparatively small, its 

 transverse section oblong and with a circle of c. 8 vascular bundles 

 that are rather close to each other some of them even not seldom 

 touching each other. On the transverse section of the petiole there 

 is a number of rather large vascular bundles in a bowed line 



Fig. 9. P. fluitans (c. 23: 1;; transverse section of the stem; 

 h, epidermis; Ik, lacunae; d, walls between the lacunae; cs, the axial cylinder: 

 the hatched parts = pith; the white parts = vascular bundles; the black parts 



= mechanical tissue. 



from one edge of the petiole to the other; and, besides this, all 

 over the transverse section, is scattered a varying number of small 

 bast bundles and a few rudimentary vascular bundles, as is nearly 

 the case in the bark of the stem. 



Quite othervise it is in the fruiting form, the Neckar-plant. 

 As pictured, fig. 9, the bark of the stem is generally quite without 

 bast- and vascular-bundles; only quite exceptionally a bundle is 

 to be seen. The epidermis is often directly adjoining the outer 

 lacunae; sometimes, however, a layer of cells exists between the 

 epidermis and the lacunae. The endodermis is an O-endodermis. 

 The axial cylinder is larger and has another outline than that of 



