30 



Transactions. 



(2.) Filling-material. — This plant resembles R. subsericea in that its 

 stems do not merely trail over the surface of the substratum, but are well 

 buried, beneath it. In no case are any mam stems visible on the surface : 

 they creep among the humus-laden soil at a depth of from 0-5 cm. to 2 cm. 

 or 3 cm. Hence it can be seen that this plant cannot possess any true 



sterevme 



cortex. 



ervdodermzs 



p&rvcyclej 



phloem 

 xyl&m 



Young stem. 



Older stem 



cortex, 



endoolermis 



stercome 

 of pericycle 



phloem 

 xyl&nv 



Very old stem. 



C. E. F. del. 



Fig. 10. — Diagrams of transverse section of stem of Raoulia Monroi, showing 

 formation of stereome in pericycle. 



filling-material. R. Monroi is really a plant with creeping and rooting 

 underground stems, such as is found in Cotula perpusilla and certain other 

 plants. 



(3.) Coloration. — The general colour effect of the mat is a silvery grey. 

 This is most obvious in a mat with the branchlets fairly close together and 

 predominating over the intermingled moss and other low herbage. The 

 greyness is due to the dense tomentum on the leaves. In winter the greyish 

 colour is slightly suppressed, owing to a development of anthocyan in the 

 leaf-margins. 



