considered in Relation to the Phyllode Theory. 463 
often lying sideways, between the lower series of small bundles and the 
lower margin of the leaf ( b v). The great development of fibrous girders (g.) 
is very characteristic and the bundles of series b V are apt to be embedded 
in them. 
The absence of phyllodic anatomy in the Dasylirions is exactly what 
might have been anticipated. The Dracaenoideae, with their tendency 
towards the tree habit, probably represent an advanced and specialized 
Figs. 36 and 37 . Dasylirion (xylem, black; phloem, white; fibres, dotted). Fig. 36 , trans- 
verse section of limb of leaf of D. longissimum , Lem. ( x i 2 |, circa ) ; b l-b v, bundles belonging to 
different series (see text); g.. fibrous girder; assimilating parenchyma. Fig. 37 , transverse 
section of leaf margin of D. Palmeri , Trelease ( x i 2 |, circa). Lettering as in Fig. 36 . 
group of the Liliaceae. Writing of the sub-tribe Nolineae, to which the 
Dasylirions belong, Trelease 1 says, ‘No reason is apparent for considering 
it to be very ancient \ The xerophytic type of leaf of the Dasylirions, with 
more than one series of bundles, all normally orientated, may be contrasted 
with the phyllodic anatomy of those externally similar xerophytic leaves 
belonging to that more primitive Tribe, the Asphodeloideae ; Dasylirion 
longissimum (Fig. 36) may be set beside Xanthorrhoea , 2 while D. Palmeri 
(Fig. 37) offers a similar contrast to Asphodelus ramosus (Fig. 8). 3 
VI. The Leaf Anatomy of Ophiopogon (Ophiopogonoideae). 
It may be well here to draw attention to the structure of the Ophio- 
pogon leaf, because it has been claimed by Schulze 4 as exemplifying an 
anomalous arrangement of xylem and phloem — the xylem of the lateral 
bundles being described as directed towards the leaf margins. This is no 
doubt an error due to the extreme fibrosis of the phloem, which makes it 
look deceptively like wood. Examination of very young leaves of 
O ._ japonicus, Ker-Gawl (Figs. 38 a and B) shows that the lateral bundles are, 
in reality, placed with the xylem directed obliquely towards the midrib. 
This somewhat unusual orientation may be paralleled in the lateral bundles of 
1 Trelease, W. (1911). 2 Arber, A. (1918), Fig. 12 , p. 479 . 
s Zuccarini, J. G. (1887-40), regards the leaf of the genus as essentially petiolar ; this may be 
correct, but it appears more probable to me that it is merely a highly differentiated leaf-base, 
4 Schulze, R. (1898). 
