455 
considered in Relation to the Phyllode Theory . 
leaves at my disposal. In the only leaf-base which I was able to section, 
I found a single series of nine bundles ; the midrib was normally orientated, 
but there was a tendency for the laterals to be placed with their protoxylem 
pointing towards the midrib (Fig. i6a). At this level there were no fibres, 
but higher up each bundle became associated with a group of sclerised 
elements. Higher still, in the limb itself (Fig. i6b), the three laterals 
on either side (l v t' v //', and / 2 , /' 2 , l" 2 ) were converted — presumably by 
branching — into three bundle-groups, while the three bundles, m, m v and 
;/z 2 , became associated into a central group, m, which also included a few 
small additional bundles, in all probability derived by branching from the 
original strands. Each bundle-group was embedded in fibres (Fig. 20). 
Figs. 20 and 21. Johnsonieae. Fig. 20, Arnocrinum Dnimmotidii, Endl. A lateral bundle- 
group from a section similar to that drawn in Fig. 16 B. It shows a group similar to / l3 including 
the three bundles, b u b%, and b 3 , embedded in fibres,/ ; xy. = xylem; ph . = phloem ; px. = proto- 
xylem ( x 250, circa). Fig. 21, Laxmannia grandijioi a, Lindl. Transverse section of central strand 
( \st .) of leaf shown in Fig. 19 c. Lettering as in Fig. 20 ( x 150, circa). 
The most significant feature in the leaf structure of Arnocrinum is the 
fact that the limb — though not the sheath — thus shows polystely . 1 This 
appears to me to have some bearing upon the 4 petiolar phyllode ’ interpre- 
tation of this leaf. Though polystelic petioles do not seem to be common, 
Petit 2 has drawn attention to certain cases. One of these, Cercis Sili- 
quastrum , L., the Judas Tree, I have examined for comparison with 
Arnocrinum. The petiole of Cercis contains one large bundle-group and 
two or more smaller ones (B, b v b 2 in Fig. 17 a), but in the midrib and main 
laterals of the lamina there are arcs of vascular tissue and all trace of 
‘ polystely ’ has vanished (Fig. 17 b). Though no great stress must be laid 
on this comparison, it seems to me that it may be held to indicate that the 
‘ polystely ’ of Arnocrinum is likely to be a petiolar rather than a ‘blade’ 
character. 
1 This term is used in a purely descriptive sense. 
2 Petit, L. ( 1887 ). 
