LYGINODENDRON 371 



seedlings or very young plants, which had not yet 

 attained their normal structure. We know that the 

 embryonic stem of an Osmunda has a continuous ring 



FtG. 137. — Lyginodcndrot oldliauiiiim. Transverse section of branching stem. At the 

 top of the figure is the base of a petiole containing two bundles. The stele of the 

 branch lies below that of the main stem. X about 4. S. Coll. 2077. From a 

 photograph by Mr. Tarns. 



of xylem, while, in the later-formed parts of the axis, 

 this is gradually replaced by a ring of distinct bundles- 

 For many years after the discovery of Lyginodendron 

 only unbranched stems came under observation, and it 

 was not till 1902 that the first cases of branching were 

 discovered by Mr. James Lomax. Fig. 137 shows, in 



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