BY E. BREAKWELL. 49 



Gi'owth-foriJi.^Tuited, bases of stems extremely bulbous and 

 hairy. Leaves rigid, pungent, and very hairy. 



Leaf-anatoiiny (Fig, 6). — In this grass, the stomata are confined 

 to the dorsal surface. Groups of bulliform cells occur between 

 the bundles. 



There are only two kinds of bundles, viz., primary (M.Bj), and 

 a special form of secondary (M.Bj). The hypoderma is thus well 

 developed under all the bundles. The primary bundles are more 

 numerous than in any of the other grasses examined Trichomes 

 are very numerous. 



Conclusion. — The trichomes, the position of the stomata, the 

 bulliform cells^ the large number of primary bundles, and the 

 well developed hypoderma, are the principal xerophytic charac- 

 teristics of this grass. 



Panicum dkcompositum (R.Br.). 



Hah. —Throughout Australia. It reaches its best development, 

 in this State, on the red and black soils of the interior. 



Growth-form. — Tufted. Stems very large and succulent. Base 

 of stems bulbous. Leaves large, wide, and rather flaccid. 



Leaf-anatomy (Fig. 7).— The epidermal cells on the ventral 

 surface are large, round, and fairly regular in size. Those 

 developed over the hypoderma, however, are smaller and have 

 thicker walls. Bulliform cells (B.), in groups of three, occur 

 between the bundles. The stomata (St.) are, for the most part, 

 arranged on the sides of the bulliform cells. Tliree kinds of 

 bundles are present, viz., primary (M.Bj), secondary (M.Bg), and 

 a special form of secondary (M.Bg). The secondary and the 

 special form of secondary are about equal in numbers. 



The hypodermal tissue (H.) is not as well developed as in P. 

 Jiavidum. Groups of colourless parenchyma-cells (U. P.) extend 

 between the bundles from the dorsal surface, about half the dis- 

 tance to the ventral surface. 



Conclusion. — This is the only Panic-grass examined, in which 

 the bands of colourless parenchyma occur, evidently adapted to 

 aid assimilation. The grass, according to its leaf-anatomy, is 

 not as xerophytic as P. favidum, and this is also borne out by 

 its behaviour in the field. 



