134 



OSMUNDACEAE 



[CH. 



Fig. 425. Transverse section of stem of Todea Fraseri, showing tlie stele (recently bifurcated), leaf- 

 traces each surrounded by a ring of sclerenchyma, and the rhomboidal bases of the leaves faintly 

 outlined. ( x 1.) (From a photograph by the late Dr R. Kidston.) 



This is not the outer surface of the leaf-base: external to it is a broad 

 band of pale soft parenchyma, which is a regularly recurring feature of 

 Osmundaceous leaf-bases. But these fit so closely together that in transverse 

 sections the appearance is given of a continuous soft matrix in which the 

 leaf-bases are embedded: and it is only when these split apart, as they 

 readily do, that the rhomboidal form of the leaf-base is recognised. Passing 

 inwards, a dense brown sclerotic zone of the true outer cortex is reached, 

 which again passes into a softer and paler inner cortex, through both of 

 which the narrowing meristeles of the numerous leaf-traces pass to the 

 centrally-lying, relatively small and pale-coloured stele. Roots originating 

 laterally from the leaf-bases may be occasionally seen taking a horizontal 

 course outwards. It is essential to be clear as to the structure thus described. 



