136 



ANCIENT PLANTS 



pointed shape. A transverse section across the apex 

 of a fertile branch shows these closely packed leaves 

 arranged in series round the axis, those towards the 

 outside show the central vascular strand which runs 

 through each. 



The markings left on the well-preserved leaf-scars 



Fig. 94. — Section across an Axis surrounded by many Leaves, which shows their simple 

 shape and single central vascular bundle v 



indicate the main features of the internal anatomy of the 

 leaves. They had a single central vascular strand (v, 

 fig- 93)' ori either side of which ran a strand of soft 

 tissue p called the parichnos, which is characteristic of 

 the plants of this group. While another similarly ob- 

 scure structure associated with the leaf is the little scale- 

 like ligule / on its upper surface. 



The anatomy of the stems is interesting, for in the 



