Vascular Anatomy of Tubers of Nephrolepis. 75 
surface of the tuber, a few millimetres inside it. In a transverse 
section of the tuber in its broadest part (Fig. 1, B) the vascular 
system appears as a ring of about a dozen or more tangentially 
flattened strands, each consisting of a plate of xylem completely 
Fig. 2. Nephrolepis cordifolia.' Transverse sections of the base of^the tuber, 
the series running from below upwards. Xylem solid black ; phloem dotted ; 
pericycle left blank ; endodermis a brokeivline ; sclerenchymatous pith cross-hatched. 
A has the appearance of a typical solenostele cut 'at a point"where it is 
uninterrupted by a leaf-gap.■'Tin B a root-stand is coming off at R, and gives 
the impression that its exit is responsible for the gap (x) seen in C and D. In 
the two latter diagrams the detached root-stand is omitted. 
surrounded by phloem, pericycle and endodermis. The xylem-plate 
is usually only one or two layers of tracheides thick, with the 
smallest elements at its two extremities. Distinctly spiral or 
annular tracheides could not be made out clearly. Bicollateral 
strands such as Lachmann found in N. exaltata were not seen. 
