Hybridization of Vitis Eotundifolia 
7 
Phloem. The arrangement of the phloem in V. vinifera is typical 
for all Euvitis species. Figure 6 is of the phloem portion of a bundle 
of V. vinifera and should he contrasted with Figure 4 of V. rotundifolia 
which is of the same magnification. In transverse section it is almost 
square in outline and is composed of alternating tangential layers of 
hard and soft bast. Thus in contrast with the Muscadinia type, the 
cambium forms first a layer of soft hast and then a layer of hard 
bast, each several cells deep, and repeating this differentiation until 
there may be as many as six or seven pairs of layers. The cells are 
arranged in radial rows and are of larger size than those of V. rotundi¬ 
folia. The hard bast cells are more angular in outline and thinner 
Availed than in that species, and the soft bast cells are much larger. 
External to the phloem of the bundle is a semicircular column of 
sclerenchyma fibers. They contrast with those of V. rotundifolia in 
being arranged in larger bundles which are semicircular, in being 
larger in diameter and very angular, and thinner Availed. 
Rays. The rays of V. vinifera (Fig. 6) are compound wood rays 
as in other Vitis species, though considerably Avider than those of V. 
rotundifolia. In contrast with these latter, they extend between the 
phloem bundles without widening through cell multiplication. Thus, 
the growth of the stem causes the cells to become pulled tangentially 
and distorted, especially at the ends of the rays. 
Cortex. As the cortex of Euvitis species is shed, the appearance in 
the cross section of the mature one year wood is quite different from 
that of the Muscadinia species (Fig. 6). The pliellogen forms im¬ 
mediately external to the phloem and inside of the sclerenchyma bundles. 
This layer of cork cells cuts off the water supply of the tissues outside 
of it, causing them to dry out and fall off. As the stem increases in 
circumference, there is no multiplication of cells as in V. rotundifolia 
so that the cells are much distorted and torn. Thus the cells in this 
region are very irregular and compacted. There are no lenticels present 
in this type of stem, the open ends of the rays serving this purpose and 
often at the time that the hark is shed, simulating them in appearance. 
V. VINIFERA X V. ROTUNDIFOLIA HYBRIDS 
Bark. Most of the hybrids of this cross have a light greyish-brown 
hark which is obscurely striated and has few lenticels, and sheds in 
small flakes rather than in fibrous plates as in V. vinifera. The appear¬ 
ance of the stems is rather smoother than that of either parent due to 
the smaller number of lenticels and a more obscure striation. I he 
number of lenticels varies inversely with the extent to which the bark 
is shed, some vines having a more or less persistent bark with many 
lenticels, and others having a loose bark and fewer lenticels and more 
striations. 
Wood. The Avood is intermediate between the two parents and is 
