igi5l 



PETRY—OPHIOGLOSSACEAE 



wing of xylem rounds up to form a single branch stele. This 

 is exactly the behavior of each of the two wings in the first specimen. 

 The vascular supply of the branch is here derived in part, at 

 least, from adaxial extension of the centrifugal xylem of the leaf 

 trace, as in B. Lunaria; but the formation of either one or two 

 wings of xylem and the consequent formation of one or two branch 

 steles is unique. The significance of this will be discussed later. 



Fig. 5. — Transverse sections of a branching rhizome of Bolrychium virginianum; 



X7- 



Botrychium virginianum. — Two branching rhizomes of this 

 species were examined; one of these bore two branches, the other 

 a single one. Fig. 5 shows the vascular connections of the branch 

 in one of these; the injury occurred at the side of the stem and 

 destroyed almost the entire stele (fig. 5, G, H). As indicated by 

 the figure, there is a development of xylem in the space between 

 the outgoing leaf trace and the stem stele, as in B. ramosum; but 



