Manchester Memoirs, Vo/. /vi. (ig] 2), No. VZ- 5 



no trace of internal phloem. A more or less complete 

 internal endodermis, which will be considered further 

 below, is often present in strong rhizomes. The xylem is 

 mesarch, the protoxylem elements being situated nearer 



F/S-. 3B- 



/"4''. 3. A. Transverse section of a large stele of //ei- 

 niinthostachys with internal endodermis. A mesarch leaf- 

 irace, the centrifugal xylem of which is commencing to 

 extend round adaxially is just departing. The disturbance 

 in the external endodermis to the left is in relation to a 

 vestigial bud. 



B. Tlie same leaf-trace in the clepsydroid stage. Tlie 

 persistence of the centripetal xylem at this stage brings out 

 clearly the distinction between the mesarch condition and 

 the adaxial completion of the xylem. Ad. , adaxial side of 

 trace. ( x 30.) 



to the inner margin of the woody cylinder. All the 

 xylem is primary but the elements of the metaxylem, 

 especially of the centrifugal xylem, tend to be radially 

 arranged. The centripetal xylem is more strongly 



