258 R. T. BAKER. 



1. Introduction. 

 Several species of plants are commonly known under the 

 name of "Mangrove,'' — belonging, however, to different 

 Natural Orders, the term being given by the layman to 

 those trees found growing in muddy, saline, foreshores. 

 Botanically, it is generally restricted to those species 

 assigned to the Natural Order Rhizophore^, but the 

 reason for such restriction is not clear. Indeed, I am in 

 favour of its being applied only to those trees which have 

 one common characteristic, i.e., the curious property of 

 having breathing roots or pneumatophores, such as Avi- 

 cennia, Laguncularia, Sonneratia, etc. As it is probably 

 impossible now to alter the common application of the term, 

 the name "Grey Mangrove" is associated in this paper 

 with the genus Avicennia, N.O. Verbenace^e, the species 

 being A. officinalis, Linn., and as this is one of Linnaeus' 

 species, its systematic position dates back a long way in 

 botanical works. 



I would like to take this opportunity of acknowledging 

 my great indebtedness to Mr. T. O. Roughley, of the 

 Scientific Staff of the Technological Museum, for the photo- 

 graphs and sections illustrating this paper ; to Mr. J. H. 

 Maiden, and Prof. A. J. Ewart for the loan of literature 

 bearing on the subject, and also to Mr.T. Dick for specimens 

 and local information. 



2, Description of the Species. 



The plant upon which the research is made may be 

 described as a species attaining full tree size, with a pate 

 coloured comparatively smooth, very thin exterior bark, 

 not much more than one-sixteenth of an inch in thickness 

 on the tallest trees. Branchlets angular, leaves opposite, 

 ovate to occasionally lanceolate, mostly acute, petiole 

 about half an inch long, margins slightly recurved, length 

 about three inches and under, breadth varying up to one 



