the Monocotyledonous Leaf . 
489 
p. 490). For, instead of the bundles all being orientated with the xylem 
upwards, as is usual in laminae, the vascular strands, though in a single 
series, are orientated, some normally (n.b.) (including the median bundle 
m.b) y the majority inversely (i.b.), and a few obliquely (o.b.), A small 
part of the transverse section is shown in greater detail in Fig. 27, p. 490. 
In this drawing the central and largest bundle is seen to be normally 
orientated, but the bundles on either side of it have the xylem below and 
phloem above. 
In the heart-shaped c lamina 5 of Heterantkera reniformis , Ruiz and 
23 
* 4 - 
Figs. 23 and 24. Fig. 23. ‘ Lamina ’ of Pontederia cordata , L. (natural size), to show venation. 
Fig. 24. A small ‘ lamina ’ of Eichhornia speciosa, Kunth (natural size), to show venation. 
Pav., a very similar bundle arrangement is found (Fig. 29, p. 490). Here 
only the midrib and main laterals are normally placed, the remaining 
bundles being inverted. 
The orientation of the bundles in these and other members of the 
Pontederiaceae closely recalls the arrangement in the leaf of Iris shown in 
Fig. 17 B, p. 483, and also that in the thinner marginal regions of the 
isobilateral leaf of Anigozanthos (Fig. 19 B, p. 483), but the flattening in 
these cases takes place in the vertical and not in the horizontal plane. 
The ‘ lamina ’ of Eichhornia speciosa , Kunth (Fig. 24), differs from that 
of those other members of the Family here considered, in its much greater 
thickness. Inverted bundles occur, not only in the thick basal region—in 
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