188 BOTANICAL GAZETTE ~- [SEPTEMBER 
surrounds each of the mestome strands. However, this parenchyma 
sheath differed from similar sheaths in other monocotyledons by 
showing no resistance when treated with concentrated sulfuric acid. 
The arrangement of the mestome strands is very peculiar, and 
especially the disposition of leptome and hadrome. From the fact 
that the blade is not a blade in the proper sense of the word, but an 
outgrowth of the dorsal face, hence with no ventral face developed, 
the course of the veins is different from that of leaves in general. If 
we examine a cross-section of the blade we notice at once that all 
the mestome strands occupy a single plane, extending from the 
one margin of the blade to the other; also that the mestome strands 
show a different position of leptome and hadrome in relation to the 
periphery of the section. Those near the center of the blade are the 
largest, and in these the leptome turns alternately with the hadrome 
to the right or left of the longitudinal axis of the leaf; in this way, 
by examining the two sides of the leaf, we find in one mestome strand 
the leptome turned toward the right, in the next toward the left, 
etc.; and the same alternating position is of course also occupied 
by the hadrome. But the small strands, which are located in the 
thin margins of the blade, show almost constantly the leptome turn- 
ing toward the edge of the leaf, and the hadrome, on the contrary, 
toward the center. In other words, the structure of the blade looks 
as if the two halves had grown together, but we know from the 
development of the leaf-primordium that no such concrescence has 
taken place. The mestome bundles are collateral and show the 
ordinary structure; anastomoses are not infrequent, and they form 
very acute angles with the larger veins, as in Eriocaulon for instance. 
The leaf structure is thus very uniform in this section, and the most 
conspicuous variation seems to depend upon the thickness of the 
epidermis, and upon whether the chlorenchyma forms typical ee 
sades (jig. 20), or consists of short, almost roundish cells, 4s in - 
anceps (fig. 21). 
In S. grandiflorum (section Ertputtema) the leaf structure differs 
very conspicuously from that of the former section, and resembles 
much more the structure of a stem than of a foliar organ. In er 
species the leaf is less compressed; the mestome strands constitute # 
narrow elliptical band, instead of being located in a single plane 
