Rhodesian species oj Fuirena , Hesperantha , Justicia. 193 
The epidermis. Cuticularization is not very pronounced, showing little 
reaction to iodine or sulphuric acid, but the area of the cuticle is increased 
by papillary outgrowths of hammer-headed form (PL XII, Fig. 14). This 
‘ granulation,’ as Rickli 1 calls it, has been described by various authors and 
considered typical of hygrophilous species in the order. Rickli found that 
it varied in the same species and was limited to the neighbourhood of the 
stomata, and, as these lie in channels, water and rain could follow the 
depressions and so swamp the apertures. The granulation, he surmised, 
would hold the water and so prevent the temporary cessation of stomatic 
function. Possibly it might have that effect and in some species may be 
more pronounced in the vicinity of the stomata, but in F. Oedipus , where it 
is particularly well developed, and in the other species examined, it occurred 
over the whole surface of the leaf, which on the vertical side is devoid of 
stomata. In the former the cuticle of the stem, with the exception of the 
basal node, shows the same peculiarity. 
The stomata consist of four cells of the usual type limited to the 
Gramineae and Cyperaceae (PI. XII, Fig. 14 a), the mechanical structure 
of which has been very thoroughly worked out by Schwendener. 2 
In considering the position of the stomata he states that in the repre- 
sentatives of steppe and desert flora they are sunk, but this condition is also 
found in the inhabitants of boggy places. The latter point is brought out 
in rather a striking manner in the present case, the stomata showing 
different positions in each of the three species collected, though all might be 
ascribed to the above habitat. In F. Oedipus , where the aerial stem is 
usually bathed in moisture, the stomata are raised above the surface of 
the epidermis (PI. XII, Fig. 12), possibly ensuring more rapid transpiration, 
which cannot go on where the surrounding atmosphere is saturated with 
water-vapour, but perhaps also the position may serve to check the lodging 
of films of water across the orifices of the stomata. In F. sub-digitata , 
where the rhizome alone is in perpetual moisture and the aerial shoots are 
exposed to full light and heat conditions, the stomata are not only sunk, 
but the cuticle of the guard-cell is produced into four papillae which project 
across the opening, almost covering it. This is precisely what Volkens 3 
has described for some Carices growing in similar situations, notably C.panicea 
Linn. The flooding during the rains to which F. sub-digitata must be sub- 
jected may also account for this development of the stomata, which in 
F. stricta are only slightly sunk and not provided with protective covering, 
though found growing in a bog medium liable to desiccation. 
The cells of the epidermis throughout the Cyperaceae show distinct 
1 Rickli, 1 . c. 
2 Schwendener, Die Spaltoffnungen der Gramineen u. Cyperaceen (Sitzungsb. K. Akad. Berlin, 
1, 1889, PP- 65-78, PI. I). 
3 Volkens, Zur Kenntniss der Beziehungen zwischen Standort u, anat. Bau der Vegetationsorgane 
(Jahrb. Bot. Gait. Berlin, iii, 1884, pp. 1-46, PI. I). 
