276 



LYCOPODIALES 



[CH. 



Miadesmia so far published we owe to Dr Benson \ whose 

 description is based on specimens from several sources. 



Miadesmia membranacea, Bertrand. Fig. 219, A — D. 



The slender stem, characterised by unequal dichotomy, has 

 a single protostele composed of scalariform tracheids with 3 — 6 

 peripheral protoxylem groups. A zone of delicate tissue sur- 



FiG. 219. A — D Miadesmia ; E Bothrodendron. 



A. Kadial section of megasporophyll : s, sporangium ; vi, mega- 

 spore ; I, ligule. (From a drawing kindly lent by Mrs D. H. 

 Scott.) 



B, C. Leaf with ligule. (From a section in Dr Kidston's Col- 



lection.) 



D. Transverse section of sporophyll. (After Scott.) 



E. Eadial section of microsporophyll of Bothrodendron. (From a 

 section in the Manchester Museum ; Hick Collection E. 406.) 



rounds the xylem ; this is described as phloem, but it is not 

 clear whether the designation is based on histological characters 

 or primarily on its position. The cortex consists of an inner 

 lacunar tissue and an outer region limited by a small-celled 

 superficial layer sharply contrasted with the underlying layers 



' Benson (08). 



