1960] 



ANATOMY OF GUAYANA XYRIDACEAE 



89 



those in the interior of the stem. The outermost layer of sclerenehyma is much 

 mbre thick-walled than interior layers, which grade into the thin-walled condi- 

 tion of the central ground tissue. Exceptionally large protoxylem lacunae, and 

 intergradation to a graminean type of bundle construction may be seen. 



Figs. 53-55. Transections of inflorescence axes, exterior at right. Fig. 53. Abolboda 

 macro st achy a var. macrostachya. Fig. 54. A. macrostachya var. robustior. Fig. 55. Orect- 

 anthe sceptrum. Scale = 0.5 mm in 0.1 mm subdivisions. 



