THE STRUCTURE OF THE STEM 



373 



found among the Equisetacece. Some species of the latter show 

 the separate bundles arranged in a ring, each with its perioycle 



Fig 759. 



Fig, 759. Stele of stem of Feru, composed of three fused concentric bundles. 

 en. Eudodennis. pe. Pericycle. ph. Phloem, px. Groups of protoxylem. 



and endodermis surrounding it (fig. 757, a) ; other species show 

 the separate bundles all fused together laterally, except that part 



F'ig. 760. Polystelic stem of Fern. st. Steles, sc. Bands of sclerenchyma. 

 hy. Hypodermal sclerenchyma. ep. Epidermis. 



of their pericycle remains between each pair. The endodermis 

 and part of the pericycle disappear from between them, but 



