674 Worsdell. — A Study of the Vascular System in 
The same is true of Jeffer sonia and Leontice ) genera not examined 
by me. 
Epimedium pinnatum , Fisch. 
In the petiole the scattered arrangement of the bundles of the cylinder is 
well marked ; there are two ranks ; the V-shaped character of the xylem is so 
extreme in some cases that the phloem is almost enclosed by it (Fig. 42). 
In the stem the ranked arrangement is almost obliterated. 
Berberidopsis corallina , Hook. f. 
Petiole : In the upper part of this organ there is a complete, transversely 
elongated cylinder in which no separate bundles can be distinguished. At 
a lower level one end of the cylinder, followed immediately after by the 
other, separates and rounds off as a distinct, perfectly concentric bundle 
with external phloem, the xylem on the ventral side of which is much less 
thick than that on the dorsal side. At the base of the petiole are three 
bundles : a central horseshoe-shaped, and two lateral concentric ones : these 
latter again become collateral in the cortex of the stem ; and all three 
unite directly with the central cylinder of the latter (Figs. 45-47). 
Akebia lob at a , Dene. 
Petiole : The numerous bundles form a complete cylinder ; at the base 
of the organ the ventral bundles pass across and fuse with the dorsal ones ; 
eventually three greatly arched, subconcentric bundles unite with the 
cylinder. 
Nandina domestica, Thunb. 
Petiole : The bundles are pronouncedly V-shaped, are in three sizes 
and more or less scattered, the largest lying innermost ; the organ is large 
and cylindrical (Fig. 43). 
Stem : The bundles are much less scattered than in the petiole ; a 
comparison between the two organs in this respect is interesting (Fig. 44). 
As regards the other plants of this order, their vascular structure 
has become much modified away from the primitive type, although the 
latter can be traced everywhere. For instance, in Berberis Darwinii Hook, 
the primitive vascular cylinder of the petiole has become reduced to an arc ; 
in the petiole of Epimedium alpinmn , L., the ranked arrangement of the 
bundles is much less distinct than is the case with the species above 
described, although the V-shaped character of the xylem is quite as 
pronounced. 
Berberis Aquifolium , Pursh. 
Leaf\ The cylindric petiole has a complete ring of nine bundles which 
becomes flattened on the ventral side lower down where the organ is 
marginally winged ; as the sheathing base is formed the ventral bundles 
