132 BOTANICAL GAZETTE [FEBRUARY 
cambium. We do not attach much importance to this varied position 
of the proto-hadrome, however, since we have ascertained that it is 
not constant, a fact that has been recorded in some previously pub- 
lished papers.° A characteristic of the root of Munroa seems to be 
the poorly developed cortex in contrast with the prominent and 
thick-walled inner tissues of the central cylinder. 
THE cutM—The long internode is semicylindric, smooth, and 
almost glabrous at the base; but cylindric, deeply furrowed, and 
scabrous above. The smooth and quite thick cuticle covers a very 
small-celled epidermis, whose outer walls are prominently thickened. 
Stomata are frequently near the furrows of the upper part of the culm, 
and their guard cells are level with the epidermis. Unicellular, 
pointed projections abound along the elevated ridges, but decrease in 
number toward the base, where the surface of the culm is smooth. 
The cortical parenchyma is well differentiated in the upper part, 
where it occurs as a single layer of palisade cells, filled with chloro- 
phyll, and bordering on the parenchyma sheath of the peripheral 
mestome bundles; the palisades are very regularly arranged, radi- 
ating from the parenchyma sheath. Another tissue of about five 
layers, but composed of colorless, more roundish cells, occupies the 
space between the peripheral mestome bundles with their covering 
of palisades, and this tissue belongs also to the cortex. It is developed 
to a somewhat larger extent at the base of the culm, where no pali- 
sades were observed; thus the cortex consists here of a continuous 
ring of colorless tissue surrounding the mestome bundles. 
The mechanical tissue as stereome is well represented and forms 
sub-epidermal groups in the ridges, bordering on the palisades, 
besides occurring as a solid, continuous zone all around the inner 
mestome bundles. Toward the base of the culm the stereome does 
not occur as sub-epidermal layers, but only as a heavy ring inside 
the cortex and surrounding both the outer and inner circle of mestome 
bundles. Throughout the culm there are thus two almost cot 
centric circles of mestome bundles, the peripheral ones being the 
smaller, orbicular in transverse section, and containing mostly lep- 
tome alone; while the larger inner ones are oval and contain both 
6 Compare: Eriocaulon decangulare L. Bot. GAZETTE 31:17. 1901; and Studies 
in the Cyperaceae. XIV. Amer. Jour. Sci. 10:278. 1 
