go 



STUDIES IN FOSSIL BOTANY 



many roots ; such a structure is very rare in stems, 

 though we find an example in the smaller branches of 

 Psilotum. In some French species of Sphenophyllum, 



Fig. 36. — Sphenopkyllum quadrifidum. A. Radial section through a node, showing 

 leaves, cut in the plane bin of Fig. B. In the middle is the stele, showing primary 

 and secondary wood, c', phloem ; d', inner, e, outer cortex ; z', leaf-trace ; /, base of 

 leaf ; m, axillary bud (?) ; n, cortical emergence below node. B. Transverse section 

 of same stem, a little above node, showing six leaves surrounding stem, a, 6, primary 

 wood ; tr, protoxylem ; c, secondary wood ; c, phloem ; d, e, cortex ; _/"', furrows ; 

 g, k, leaves, each with four vascular bundles. C. Transverse section through a node, 

 showing the forking leaf-trace bundles, j\j. Other lettering as before. A, B, C X 9. 

 D. Transverse section of a portion of secondary wood, c, tracheides ; jt, parenchyma 

 between them. The radial direction is vertical in this figure, x about 60. All after 

 Renault. 



described by M. Renault, the protoxylem-groups are 

 double, 1 so that here the wood may be described as 



1 The scale of Fig. 36, B and C, is too small to show this point. Cf. s 

 however, Fig. 41, B. 



