490 
Agnes Arher .— The Phyllode Theory of 
Figs. 25-30. Pontederiaceae. Fig. 25. Eichhornia spcciosa , Kunth. Transverse section of 
lateral vein of ‘ lamina ’ (x 200 circa). One small normal bundle (n.b.). One larger inverted bundle 
(?./>.), higher in leaf, is giving off a branch, also inverted. /. = fibres; ph. = phloem ; xy. = xylem. 
Fig. 26. Pontederia cordata, L. Half transverse section of lamina near apex ( x 23). All bundles 
inverted (i.b.) or oblique (0.6.) except the median bundle (m.b.) and the three bundles n.b., n.b.' , and 
n.b." Fibres {/.) at margin ; h.b. = horizontal branch. Fig. 27. Pontederia cordata , L. The part 
of the transverse section shown in Fig. 26 which is included between the dotted arrows ( x 200 circa). 
One normal bundle (n.b.) and two inverted bundles (i.b.), one with an inverted branch, m.c. = cells 
containing a secretion, probably myriophyllin. Fig. 28. Pontederia cordata, L. Transverse section of 
petiole near its upper end, outlines of lacunae dotted ( x 23). Fig. 29. Heteranthera reniformis , Ruiz 
and Pav. Part of transverse section of lamina, including midrib ( m.b .) (x 23). All the bundles 
shown are inverted, except the midrib and main lateral, s. = bundle sheath. Fig. 30. Heteranthera 
zosteraefolia , Mart. Transverse section of part of ribbon leaf ( x 200 circa), to show one normal and 
one inverted bundle. 
