46 XEROPHYTIC NATIVE GRASSES, 



The grass has a very distinct midrib. The mid-primary bundle 

 is very large, contains well developed xylem-elements, and is 

 bounded dorsally and ventrally by a large development of hypo- 

 derma. There are three primary bundles in the midrib, and the 

 development of uncoloured parenchyma-cells on the dorsal surface 

 is large. 



The bundles are confined mostly to the primary (M.Bj) or the 

 intermediate (M.B4) types. The latter are characteristic, being 

 close to the ventral surface, open, and bounded by hypoderma. 

 There is, thus, a large development of palisade-tissue towards the 

 dorsal surface. 



Conclusion. — This grass presents some characteristic features. 

 The harsh, rigid character of the leaves in the field is due to the 

 extreme development of hypodermal fibre, greater, perhaps, in 

 this grass than in any other examined. 



On this development of hard tissue, and on the bulliform cells, 

 the grass evidently depends for its xerophytic characteristics. 



ASTREBLA PECTINATA F.V.M. 



Hab.—^ew South Wales, Queensland, Northern Territory, 

 Western and South Australia. In this State, it is found both 

 on the red and black soils in the northern and western interior. 



Growth-form. — Tufted, bases of stems bulbous. It is particu- 

 larly characterised by the rapidity with which leaf-growth takes 

 place at the joints under moist conditions. 



Leaf-anatomy (Figs. 4-5). — The epidermal cells of the ventral 

 surface are much larger than those of the dorsal. The cuticle is 

 moderately thick, but not so thick as in Spinifex hirsutus Labill. 



The stomata (St.) are confined solely to the dorsal surface, and 

 are on the sides of groups of bulliform cells. The latter (B.) are 

 in groups of five. The middle bulliform cell is the largest, and 

 the two on each side of decreasing dimensions. There appears 

 to be no doubt, from the shape and arrangement of these cells, 

 that they aid in closing the leaf, in which case the stomata would 

 be hidden. 



The bundles are of three kinds, viz., primary (M.Bi), secondary 

 (M.B3), and a special form of secondary (M.B2). The primary 



