182 BOTANICAL GAZETTE [MARCH 
frequent, but only on the lower face (jig. 31). The cuticle is wrinkled 
on the upper face, but smooth on the lower, except over the hairs, 
where it is minutely granular. The epidermis is thin-walled; uni- 
cellular, seldom bicellular, hairs cover the lower face, especially the 
nerves; they are quite thick-walled and the apex is pointed and more 
or less curved. The stomata, which are confined to the lower face, 
have two subsidiary cells, one of which is mostly much smaller than 
the other, but they are both parallel with the stoma. A cross-section 
of the leaf (fig. 32) shows the lumen of the epidermis to be about 
the same on both faces; also the structure of the chlorenchyma, which 
shows a palisade tissue quite well distinguished from the underlying, 
very open, pneumatic tissue (jig. 33). A small group of collenchyma 
and water-storage tissue is located underneath the median and the 
two lateral mestome bundles. The structure of the veins agrees in all 
respects with that observed in the former species. Besides the secre- 
tory cells in the epidermis, there are in the pneumatic tissue many 
cells containing raphides. 
In G. circaezans the collenchyma reaches a high development in 
the stem, but not in the leaf. The epidermal secretory cells show 
the same structure as those of G. pilosum, but the cuticle is uniformly 
smooth over them, not striate as in G. pilosum. The leaf structure 
is bifacial, even if the palisades are not quite typical. 
G. LATIFOLIUM 
In habitus this species resembles very much the preceding, but 
is more robust, taller, with coarse stems and larger leaves. The 
primary root does not persist, but secondary ones are developed in 
great numbers; they are yellowish-brown, quite thick, and branch 
freely. This species has no true rhizome, but a pseudo-rhizome of 
densely matted basal internodes, that persist for several years. The 
foliage of these over-wintering stem portions is reduced to small, scale- 
like leaves of the same length as the internodes. The aerial shoot 
is stout, with several lateral branches, all of which are terminated 
by inflorescences. : 
The roots.—The secondary roots are glabrous, and the epidermis 
is thin-walled. A compact cortex of three strata borders on the endo- 
dermis, of which the cell walls are moderately thickened; the peri- 
