192 
Gibbs . — Bio-histological notes on some new 
several internodes which, at the point where the rhizome bifurcates in the 
formation of the aerial stem, instead of elongating like the others, remain 
short and swell to a considerable size, the rest of the rhizome being slender 
and wiry. In grasses, tuberous swellings involving the lowest internodes 
of the culm and foliage-shoots (Knollen-Graser) or the base of the leaf- 
sheaths (Zwiebel-Graser) are common. According to Hackel 1 these are 
characteristic of species inhabiting regions of periodical drought, where 
they serve as water reservoirs, he having never found any reserve material 
in them, at whatever season examined. 
The late Mr. C. B. Clarke, whose knowledge of the Cyperaceae was 
unrivalled, was much struck by this plant, to which he gave such a peculiarly 
appropriate specific designation. A similar modification was unknown to 
him in the order. 
The leaf. In this species the lamina is 6-7 mm. broad, 15-18 cm. 
long, with five prominent nerves on the dorsal side, corresponding to the 
same number of grooves on the ventral surface, which is covered with 
unicellular hairs, such as, according to Rickli 2 , are typical of Fuirena. 
The structure of the leaf is very interesting owing to the extreme 
differentiation of the epidermis on the ventral surface, the cells composing 
it being thin-walled and enormous in size. (PL XII, Fig. 12, v.e.) 
As the genus Fuirena has been hardly touched upon in work on other 
families in the order, sections were cut of the leaves of two other species 
collected in the same season in the Matoppo Hills, but found growing under 
different conditions and showing a more xerophytic habit. For purposes 
of comparison these are now described. 
Fuirena stricta Steud. A plant of very wide distribution throughout 
tropical Africa and the Mascarene Islands. It was growing in a bog, in 
probably a stagnant and acid substratum. The stem is triangular, with very 
long internodes almost covered with nearly equally long leaf-sheaths, the 
laminae of which are very much reduced, being narrow and very short. 
The scale leaves of the rhizome and the lower stem-internodes are 
membranous. In this case the cells of the epidermis on the ventral surface 
of the leaves are large. Fuirena subdigitata C. B. Clarke 3 shows a more 
hygrophilous habit, but the structure of the leaves is very xerophytic in 
type. The laminae are considerably longer than the encircling leaf-sheaths. 
The stem is triangular, with long internodes not entirely covered by the 
leaf-sheaths. This plant was growing on damp sand-banks in a stream, the 
roots therefore in moisture, while the aerial shoots would be exposed to 
powerful illumination. The scale leaves are in this case very hard and 
persistent, possibly to withstand the effects of inundation in the rainy season. 
1 Hackel, Ueber einige Eigenthumlichkeiten der Graser trockener Klimate (Verhandl. Zool.- 
Bot. Ges. Wien, 1890, pp. 125-136). 
2 Rickli, 1 . c. 
8 Gibbs, 1 . c., p. 477. 
