1916] HOFFSTADT—PIPER METHYSTICUM 129 
stem (fig. 20). In two cases it was observed that the branch did 
not develop in the axil of a leaf where only the blade was developed 
(fig. 21), which was due probably to the pressure caused by the 
enveloping sheaths of the preceding leaves. 
Piper umbellatum 
The stem of Piper umbellatum is not essentially different from 
that of Piper methysticum. At maturity it has only one ring of 
pith bundles. The bundles, instead of traversing two nodes as 
internal bundles before fusing with the next group, traverse but 
one (fig. 22). The young plants are covered with hairs, both uni- 
cellular and multicellular. The number of leaf traces is 7-9. In 
the young stem there is an abundance of mucilage scattered in all 
regions. In the old stem a single mucilage canal appears in the 
center, which is continuous through the nodes and in the branches; 
VAN TIEGHEM found none that was continuous through the nodes 
(fig. 23). 
Summary 
1. The stem of Piper methysticum consists of two systems of 
bundles, peripheral and pith, the latter being in two rows. : 
2. The peripheral bundles are of two sizes: primary, the larger; 
secondary, the smaller. The latter are branches of the former. 
3. The bundle type is collateral endarch. 
4. The bundles are of foliar origin. 
5. The bundles, after entering the stem, remain in the periph- 
eral region through one internode and then traverse the. pith 
for two internodes. 
6. Both the peripheral and pith bundles show anastomoses. 
7. The pericycle consists of only a few ig outside the bundles, 
which become lignified. 
8. There is no differentiated endodermis. 
9. The stem enlarges by cambial activity and divisions in the 
pith region. 
ro. An interfascicular cambium appeats late in the internode 
and cuts off segments only on one side; it comes still later in the 
nodes. 
