ANATOMY AND AFFINITY OF CERTAIN RARE AND PRIMITIVE FERNS. 381 
Axis . — Storage parenchyma bulks largely in the ground-tissue of the axis, and 
only a narrow peripheral zone is sclerotic. The vascular system is a solenostele, the 
only gaps in which are leaf-gaps (fig. 45). As will be seen from this stelar recon- 
struction, and from the series of diagrams in text-fig. 16, the leaf- trace consists of two 
similar curved strands. These are inserted laterally towards the base of the leaf-gap. 
The root-traces are in oblique series outside and beneath the insertions of the leaf- 
traces, and are commonly branched near their points of origin. 
Root . — The root is sturdy, and has abroad, thick-walled cortex (fig. 47). It shows 
no features which can be used in a discussion of affinity. 
Text-fig. 16 . 
Leaf . — In the base of the petiole the two leaf-trace strands are strongly curved. 
The xylem-margins are “ hooked,” and breaks in the continuity of the tracheides are 
common (text-fig. 17). As the petiole is ascended the strands undergo condensation 
but retain their relative positions. The chief steps in the supply of the first pair 
of pinna-traces are represented in text-fig. 18. As will be seen from the series of 
diagrams (a)—(f), the margins of the xylem become first united to the main body 
of tracheides, and the pinna-trace supplies are. thus of extra-marginal origin. The 
second pair of pinna-traces are similarly supplied. A union of the two leaf-trace 
strands now occurs (text-fig. 19), and the supplies to the third pair of pinnae are 
extra-marginal in origin (text-fig. 20 (a)-(f)). In our plants the supplies to the 
fourth, fifth, and sixth, and occasionally the seventh, eighth, and ninth, pairs of 
