1908] HOLM—SISY RINCHIUM 189 
also the central portion of the leaf contains a thin-walled, colorless 
tissue very much resembling the pith of a stem, and is frequently 
hollow. Otherwise the structure of the tissues is identical with that 
of several species of the former section (BERMUDIANA). ‘The cuticle 
is thick, but smooth; the epidermis is papillose, moderately thick- 
walled, and the chlorenchyma is composed of palisades, which are 
vertical to the epidermis but very open from wide intercellular spaces. 
The stereome is rather thin-walled, and shows the same distribution 
as in BERMUDIANA, The leaf is very distinctly furrowed longitudi- 
nally, and the mestome strands, which are of two sizes, are arranged 
alternately so that the smaller are in the furrows and the larger in 
the ridges. All the mestome strands turn the leptome toward the 
periphery of the blade, while the hadrome borders on the thin-walled 
parenchyma, which fills the innermost portion of the blade, thus 
resembling a pith in respect to structure and position. 
In the section Ecururonema the principal structure of the 
blade agrees better with that of ERIPHILEMA than of BERMUDIANA; 
because the mestome strands are here also in a very narrow elliptical 
band with the hadrome turned inward and bordering on a central, 
thin-walled parenchyma. In S. californicum the cuticle is thin and 
smooth; the epidermis is relatively thin-walled and perfectly glabrous. 
The chlorenchyma (fig. 18) shows no palisades, but is composed of 
a homogeneous tissue of oblong to roundish cells (in cross-section) ; 
however, a superficial section of the blade (fig. 17) shows the cells 
of the chlorenchyma very distinctly stretched and lobed, not parallel 
with the longitudinal axis of the leaf, but vertical to it. In this way 
the chlorenchyma shows actually the structure of a pneumatic tissue, 
as this js developed in the dorsal portion of leaves; the central part 
of the chlorenchyma in this species is also a colorless, thin-walled 
parenchyma. No stereome was observed, and the mestome bundles 
are in a narrow elliptical band; they are collateral and surrounded 
by thin-walled parenchyma sheaths. Lae 
is is in brief the anatomical structure of these species of Sisyrin- 
chium, and bearing in mind that representatives of each of the three 
sections have been examined, it appears to me that the genus 1s a 
very natural one, and that it ought not to be divided. In regard to 
the morphological structure of the shoot, I have not been able to 
