BY LEONARD lloDWAY, GOVERNMENT BOTANIST. 63 



Treubia is of great interest to the Bryologist, for it 

 combines reproductive and frtiiting characters of Aneur- 

 aceae with the leafy morphology of the Acrogyneae. Many 

 authorities try to avoid the breaking down of established 

 systems by treating the lateral expansions as lobed portions 

 of lateral wings. This seems a distorted description of the 

 apparent structure, and does not tend to a clear under- 

 standing of the evolution of the hepatics. The leaves of 

 this group of plants have without doubt arisen independ- 

 ently along many lines of descent, and also^ have arisen by 

 the transformation of very different primary structures- In 

 some instances they have arisen by the gradual modifica- 

 tion of protective scales or from mucilage-secreting organs ; 

 or again as lateral expansions which have from, the first, or 

 subsequently, been segmented into the condition that we 

 have generally called leaves. We must always remember 

 that leaves of mosses and leaves of flowering plants are only 

 alike in name and function. They can have no relation- 

 ship one to another. They belong to different categories, 

 and cannot truthfully be compared, except -so far as their 

 function- 



If the term leaf is to be applied to definitely structur- 

 ed, lateral, assimilatory organs of Hepaticse, then Treubia 

 is leafy and not merely frondose. It is only a difference of 

 words, with the addition of some recognition of evolution- 

 ary developments. 



