52 
Lang.—Studies in the Morphology and 
Photo 2. Similar portion of the vascular tube from a smaller rhizome; the inner xylem' is 
represented by scattered elements, x 67. 
Photo 3. Similar portion of the vascular tube from a rhizome with irregularly developed inner 
xylem; in the centre of the portion figured the protoxylem abuts on the parenchyma of the 
pith, x 67. 
Photo 4. Transverse section of a large adult rhizome, showing the stele, from which a leaf-trace 
has departed, leaving the leaf-gap. The leaf-trace is seen in the clepsydroid stage in the cortex. 
The basal connexions of two roots with the stele are shown, x 25. 
Photo 5. Leaf-trace from the adult rhizome figured in Photos 4 and r, and Plate II, Photos 20, 
21, showing an advanced stage of the adaxial extension of the xylem. The protoxylem of the trace 
has divided in preparation for the division of the trace ; internal to each of the two groups of 
protoxylem, a small amount of inner xylem persists. x 67. 
Photo 6. Same leaf-trace as in the preceding photograph, but a little further out (cf. Photo 4). 
The outer xylem is complete adaxially, and a band of tracheides connects the abaxial and adaxial 
portions, dividing the central parenchyma into two portions. In each of them remains of the inner 
xylem are still present in front of the protoxylem groups, x 67. 
Photo 7. Dorsal portion of a stele of a small rhizome, showing to the right the disturbance of 
the endodermis in relation to a vestigial bud and on the left the arc of xylem for a leaf-trace; 
the inner xylem is almost wanting within the protoxylem of the trace, x 67. 
Photos 8, 9. Two stages in division of the leaf-trace seen in Photo 7. The division takes place 
without adaxial completion of the xylem, though a number of metaxylem elements are present 
internal to the protoxylem groups, x 67. 
Photo 10. Transverse section of a leaf-trace from a small rhizome (that in Text-fig. 4), showing 
endarch xylem with no adaxial completion of the outer xylem. x 67. 
Photo 11. Transverse section of the leaf-trace shown departing from the cortex of the large 
rhizome in Text-fig. 6. The trace is monarch, the xylem has closed round to form a complete tube, 
and the protoxylem is separated from both the adaxial and abaxial regions of the xylem by 
parenchyma, x 67. 
Photo 12. Transverse section of another leaf-trace from the same rhizome, showing the monarch 
trace, the absence of inner xylem, and the adaxial extension of the outer xylem still incomplete, 
x 67. 
Photo 13. The same trace as in Photo 12, a little further out. The adaxial extension of the 
xylem is complete, and the phloem also forms a complete tube, x 67. 
Photo 14. Dorsal portion of the stele of the rhizome in Text-fig. 8, showing the preparation for 
the departure of the third leaf-trace. The adaxial extension of the outer xylem is happening 
as the arc of xylem separates, x 67. 
Photo 15. Further stage than Photo 14. The adaxial xylem is complete, but is still continuous 
with the xylem of the stele, x 67. 
Photo 16. The same leaf-trace in the cortex, showing the complete tube of phloem. The 
xylem of the trace is still monarch, x 67. 
Photo 17. The same leaf-trace in the clepsydroid stage, x 67. 
Photo 18. Similar but larger leaf-trace from the same rhizome in the clepsydroid stage, x 67. 
Photo 19. One of the halves into which this trace divided (cf. Text-fig. 8 , e), showing the 
preparation for the next division, x 67. 
PLATE II. 
Photo 20. Dorsal portion of the stele of the rhizome represented in Text-fig. 2, c. To the left 
the nascent leaf-trace is seen with the inner xylem diminished in amount but not wanting. To the 
right is the closed leaf-gap with the greatly developed inner xylem continuous across and extending 
outwards into the gap still present in the outer xylem. Above this the endodermis is raised and 
open in relation to the vestigial bud. x 67. 
Photo 21. Similar section, corresponding to Text-Fig. 2,D, showing the full development of 
the bulge of xylem in relation to a vestigial bud. The bulge consists of inner xylem covered by 
outer xylem, while the outer xylem is also extending across below to complete the xylem ring of the 
main stele, x 67. 
Photos 22-24. Stages in the departure of the vascular supply from the first branching specimen. 
