592 BRITTON: VEGETATION OF THE 
on the under surface opposite nearly every mestome bundle, and 
on the upper surface each side of the bulliform cells. Bundle of 
the keel is partly surrounded by a sheath of stereome. Each 
mestome bundle has a sheath of large green parenchyma-cells. 
Epidermis of edges and under surface composed of small cells 
with rather thick outer walls. Stomata all on under surface, not 
depressed. Chlorenchyma-cells are arranged radially around the 
mestome bundles. On each side of the bundles and alternating 
with them is a row of cells or ducts containing a brown substance, 
probably tannin. A transverse section of the leaf is figured (f/. 
26, d).* 
STENOPHYLLUS CAPILLARIS. — Leaf has six rows of bulliform 
cells on the upper surface above the keel. There are only three 
bundles, one in center, and one on each side. There are five 
stereome strands, two on upper surface at edges of the layer of 
bulliform cells, and three on lower surface, one in keel and one on 
each side opposite those of the upper surface. Epidermis of lower 
and lateral surfaces is made up of small cells with rather thick 
walls. Each bundle has a sheath of stereome inside of which is 
a sheath of green parenchyma-cells. The central vascular bun- 
dle has the elements well developed but in the other mestome 
bundles the leptome and hadrome are not well differentiated. Sto- 
mata occur in the hollows of the lower surface each side of the 
keel and along the lateral surfaces between the stereome strands. 
Occasionally an upper or lateral epidermal cell is prolonged into a 
short, stout spine or hair. Certain cells or vessels are filled with 
a brown substance, probably tannin, similar to that found in Cype- 
rus filiculmis. The assimilating cells radiate from the vascular 
bundles. A cross-section of the leaf is shown (f/. 26, /): 
The stem is star-shaped in transverse section, having five points, 
a heavy strand of stereome occurring beneath the epidermis of 
each point, and opposite a vascular bundle. Two of the bundles 
are larger than the other three and have the elements well devel- 
oped ; the three smaller ones are not clearly divided into leptome 
and hadrome. Each bundle has a stereome sheath with sheath of 
green parenchyma inside like the leaf-bundles. Epidermis is made 
up of colorless cells with rather thick outer walls. These cells 
* See also O’ Brien, /. c. 
