322 



FILICALES 



[CH. 



palmatum the lamina is deeply lobed. In the genus Botry- 

 chium, represented in Britain by B. Lunaria, both sterile and 

 fertile branches of the frond are pinnately divided, while in 

 Helminthostachys the sporangia are borne on sporangiophores 



Fig. 246. Ophioglossum vulgatum. Transverse section of petiole and single 

 bundle : p, phloem ; px, endarch protoxylem. 



Fiu. 247. Botrychium virginianum: e, endodermis ; c, cambium ; x, xylem. 

 A, diagrammatic section of stem; B, portion of the stele and 

 endodermis enlarged. 



(A, after Campbell ; B, after Jeffrey.) 



given off from the margin of the fertile branch of a frond 

 similar in habit to a leaf of Hellehorus. 



The stem of Ophioglossum is characterised by a dictyostele 

 of collateral bundles with endarch protoxylem: the vascular 

 system of the leaf-stalk is also composed of several separate 



