49 
Anatomy of the Ophioglossaceae . III. 
is poorly developed there may be a more or less direct continuity of the 
parenchymatous pith of the root and rhizome. The pith in the root base 
sometimes has a well-marked internal endodermis independent of that often 
found in the rhizome. 
4. The dorsal side of the stele is disturbed by the leaf-traces and in 
relation to the vestigial buds. 
The leaf-trace exhibits considerable variety in its mode of departure, 
structure, and mode of division in the cortex. In large rhizomes it may 
depart as a mesarch portion of the stelar tube, though the inner xylem is 
always less developed within the trace, and gradually dies out as the latter 
departs. In other cases the inner xylem disappears from the nascent leaf- 
trace, which departs with an endarch xylem. 
The leaf-trace, whether mesarch or endarch, may divide into two in the 
cortex without adaxial completion of the outer xylem or the other tissues. 
More usually, this adaxial completion of the xylem takes place before 
division, and the phloem as well as the endodermis may also be completed. 
Adaxial completion may take place just before division of the trace; in 
other cases the xylem is completed adaxially while the trace is still 
monarch, and sometimes even before its xylem is free from that of the stele. 
This condition, in which the monarch trace has a complete ring of outer 
metaxylem surrounded by phloem and endodermis, may persist until the 
undivided trace leaves the rhizome. Usually, however, division of the trace 
is effected, and just before this the leaf-trace has a dumb-bell-shaped outline 
with a protoxylem group in each half, the metaxylem being continuous 
from the abaxial to the adaxial xylem between the two protoxylem groups. 
This has been termed (followingC. E. Bertrand and Cornaille) the clepsydroid 
stage. 
In leaf-traces which are mesarch and also show adaxial completion of 
the xylem, a clear distinction can be drawn between the two conditions; 
they both involve the presence of metaxylem to the inside and outside of 
the protoxylem, but are essentially different. The leaf-traces of small 
rhizomes are always endarch at departure, and may or may not exhibit 
more or less complete adaxial extension of the xylem. 
5. The disturbance of the stele in relation to the vestigial axillary buds 
varies in degree, being most marked in the case of large adult rhizomes, 
and wanting in many smaller ones. In all cases, however, the endodermis 
remains open, or opens again, in relation to the dormant lateral apex. In 
well-marked examples, the bulge of xylem behind the bud corresponds to 
the stele at the base of a lateral branch in consisting of inner xylem 
surrounded by outer xylem, both being continuous with the corresponding 
tissue of the main stele. 
The vestigial bud is in relation to the subtending leaf, and exhibits 
some variety in position relatively to the corresponding leaf-gap; it is 
E 
