184 BOTANICAL GAZETTE [SEPTEMBER 
RHIZOME 
S. calijornicum is the only species examined that possesses a hori- 
zontally creeping rhizome with the internodes distinct. The struc- 
ture is rather weak when compared with that of the rhizomes of the 
monocotyledons in general, since no stereome is developed. The 
epidermis is thin-walled and covers a cortex of broad, compact 
parenchyma; the endodermis is thin-walled, and the cells somewhat 
irregular in shape. Inside the endodermis is a large, thin-walled 
pith, in which the numerous mestome strands are located, but without 
being arranged in bands; most of these mestome bundles were 
observed to be leptocentric, the leptome being more or less com- 
pletely surrounded by the hadrome. 
STEM ABOVE GROUND 
With exception of S. grandiflorum the stem is ancipital, simple, or 
sometimes branched above; the wings vary somewhat in breadth, 
but the central portion of the stem is always cylindric, and of a very 
firm structure, due to the presence of a solid sheath of thick-walled 
stereome. The cuticle is frequently thick and wrinkled, and cell 
walls of the epidermis are prominently thickened, especially the 
outer, and very often extended into short papillae, but not in J. 
californicum. In the body of the stem as well as in the wings the 
cortex is composed of palisades and represents a very compact tissue, 
but in S. californicum the cortical parenchyma is more open and the 
cells very short, almost roundish in transverse sections. There is 20 
hypodermal collenchyma or stereome in any of these species, and the 
stereome constitutes, as stated above, a closed sheath of several 
strata located on the inner face of the cortex in the cylindric portion 
of the stem; in the wings the stereome accompanies the larget 
mestome strands as small groups on the leptome side. The mestome 
bundles are arranged in two concentric bands in the cylindric part 
of the stem, but in a single plane in the wings. They are collateral, 
and those of the peripheral band are very small, and contain mostly 
leptome; they are located in the cortex, but their hadrome touches 
the stereomatic sheath. Those of the inner band are much large 
and are located directly inside the stereome cylinder, with sage 
hadrome bordering on the pith. The innermost part of the cylinder 
