492 
Agnes Arber .— The Phyllode Theory of 
phyllodic anatomy of the 5 lamina \ The present writer has found in the 
arrow-head blade of Sagittaria montevidensis, Cham. and Schlecht. (Fig. n, 
p. 479, and Fig. 32), that, besides the normal main bundles [n.b. 1) 
and a series of smaller bundles running near the lower surface [n.b. 2), 
there is a third series of small inverted bundles near the upper surface [i\ b.). 
Figs. 31 and 32. Sagittaria. (n.b. 1 = bundle of main normal series ; n.b. 2 — bundle belonging 
to second normal series; i.b. = inverted bundle ; xy. = xylem; ph. = phloem ; a.t. = assimilating 
tissue; st. = stoma; o.d . = oil duct). Fig. 31. Sagittaria sagittifolia, L. Transverse section of lateral 
vein of lamina, next but one to midrib (x 400 circa). Fig. 32. Sa 8 ittaria montevidensis , Cham, 
and Schlecht. Small part of transverse section of leaf near margin in region between arrows in 
Fig. 11, p. 479 ( x 100 circa). The lower of the two bundles belonging to the normal series (n.b. 2) is 
irregularly placed. Fig. 32 shows that in this genus the inverted bundles are not confined to the ribs. 
In Sagittaria sagittifolia , L., inverted strands are a less striking feature, but 
the lateral ribs, one of which is represented in Fig. 31, show both normal 
and inverted bundles. 
The present writer has not yet succeeded in finding inverted bundles in 
the blades of any other Family, except the Hydrocharitaceae, in which their 
existence was already known. In this Family such bundles occur not only 
in the undifferentiated leaves of Enalus 1 and Stratiotes , 2 but also in 
1 Magnus, P. (1870). 
2 Solereder, H. (1913). 
