PAST HISTORIES OF PLANT FAMILIES 



117 



The roots of Lyginodendro7i, when young, were like 

 those of the Marattiaceous ferns, their five-rayed mass 

 of wood being characteristic of that family, and different 

 from the type of root found in most other ferns (cf fig. 7 8b 

 with fig. 35 on p. 60). Unlike fern roots of any\ind, 

 however, they have well-developed zones of secondary 



Fig. 78E. — Transverse Section of Root oi Ljginodendron 



w, Five-rayed mass of primary wood ; s, zone of secondary wood ; c, cortical 

 and other soft tissues. 



wood, in which they approach the Gymnospermic roots 

 (see fig. 78B, s). 



A further mixture of characters is seen in the vascular 

 bundles of the petioles. A double strand, like that in 

 the lower Gymnosperms, goes off to the leaf base from 

 the main axis, but in the petiole itself the bundle is like 

 a normal fern stele, and shows no characters in transverse 

 section which would separate it from the ferns. Such a 

 petiole is illustrated in fig. 79, with its V-shaped fernlike 

 stele. On the petioles and stems were certain rough, 

 spiny structures of the nature of complex hairs. In some 



