FLORA OF THE HAWKESBURY SANDSTONE 223 



natural orders. In Dillwynia ericijolia and D. floribunda there 

 is a thickening of the margins, so that there is a V-shaped groove on 

 the under side, and through a twist in the leaf this runs in a spiral 

 direction. The groove is lined with thick-walled tapering hairs. 



True sunken stomates are found in the flat leaved Banksias. 

 On the under side of the leaf there are numbers of cavities or crypts 

 of a hemispherical shape or spherical with a narrow mouth. The 

 cavities are lined with hairs having a bulbous base crowned by a fine 

 curled hair or cilium. There are many of these in each crypt, and 

 the fine cilia are fitted into a plug projecting from the mouth of the 

 cavity.^ In all the flat-leaved Banksias I have sectioned, including 

 a number from West Australia, the hairs have this form. The 

 stomates are very large and there are from sixteen to twenty in each 

 crypt. Each crypt is margined by a vein. The palisade is very close 

 and there is a patch of open spongy tissue surmounting the roof of 

 each cavity. The same structure is found in Neriiim Oleander, but the 

 hairs are not the same type, and the crypts occur on both sides of 

 the leaf. There is an approach to crypt formation in Ficus macro- 

 phylla, and in an Italian paper, the reference to which I have un- 

 fortunately mislaid, the authors describe crypt structure in certain 

 tropical figs. 



In Casimrina, the stomates are on the sides of grooves running 

 along the branchlets from node to node. The grooves are lined with 

 thick-walled branching hairs. There is a differentiation between 

 the base and the extremity of the hairs, the extremity staining 

 readily and deeply with saffranin, while the base remains uncoloured. 

 The palisade tissue is small in quantity and lies in the lobes between 

 the grooves. Between it and the epidermis a thick layer of scleren- 

 chyma is interposed and a wedge of the same runs down the centre 

 of the palisade. 



The increased number of air-containing cells I have not noticed 

 except in the epidermis of some of the plants. 



Water-storing cells are found in Portulaca, Claytonia, Rhagodia 

 and Mes3mbryanthemum. 



The section of wax and other protective substances on the 

 surface is extremely common. It is generally the young leaves 

 which are protected in this way. Eucalyptus corymbosa has the 

 young foliage coated with rubber. * Dodoncca has its leaves coated 

 with a viscous substance which persists when the leaf is full grown. 



Hairiness is not a general adult character. Actinotus shows it 

 in a marked degree. Metrosideros glomiilifera, Callicoma and some 

 others have the underside of the leaf, where the stomates occur, 

 covered with hairs. In the former the hairs often disappear with 

 age. Hairiness is much more common on the younger leaves. 

 Several of the flat-leaved Banksias and some of the flat-leaved 

 Hakeas show it. The young shoots are so thickly covered with 

 golden brown hairs that they look like chenille or fur. 



