42 



THE ANATOMICAL STRUCTURE OF SOME 

 XEROPHYTIC NATIVE GRASSES. 



By E. Breakwell, B.A., B.Sc. 



(Thirteen Text-figures.) 



The grasses examined were : — Spiiiifex hirsutus Labill., (male 

 plant), Fanicum flavidwni Retz., Themeda avenacea Hackel, 

 Astrehla pectinata F.v.M., Neurachne Mitchelliana Nees, Pani- 

 cum decGmposituni R.Br., Chloris acicularis Lindl., PanicuTn 

 leucophcmim H.B.K., P. Benthami Domin, Eragrostis lacunaria 

 F.V.M., and E. curvula var. valida Stapf. These grasses, with 

 the exception of the first, were obtained from the Nyngan 

 district. 



Spinifex hirsutus Labill., (male). 



Hah.— On the sea-shores throughout Australia, New Caledonia, 

 and New Zealand. 



Growth-form. — Grows in the form of tufts. Stems creeping at 

 the base. Leaves intensely hairy, felted in appearance, and soft. 

 The ventral surface is much more hairy than the dorsal. The 

 latter surface is thrown into depressions. 



Leaf-anatomy (Fig.l). — A transverse section of a leaf shows a 

 thick cuticle. The epidermal cells on the ventral surface are 

 fairly regular in character, mostly rounded, and small-lumened. 

 The stomata (St.) on this surface are numerous, and, in all cases, 

 sunk in depressions. These depressions are formed by the cells 

 bounding the stomata assuming a cylindrical shape, and being 

 raised above the general level of the epidermal surface. The 

 epidermal cells of the dorsal surface are larger than those of the 

 ventral. The former surface is thrown into ridges of two dis- 

 tinct consecutive sizes, viz., a smaller one to be followed by one 

 twice its depth. 



The epidermal cells on the crests of the larger ridges are two- 

 layered, and smaller than those bounding the smaller ridges. 



