183 





Fig. 30. Ephedra alata. A, Transverse section of bark 

 of a young branch. B, T. S. of a year-old branch. X 230. 



The anatomical structure of the green bark is briefly 

 described by Volkens (p. 151), and Ross (p. 17) describes 

 an undetermined Ephedra species. Fig. 30 shows the 

 assimilating cortex of a young and of a somewhat older branch. 

 The outer wall is very thick with a strong cuticularised 

 layer. The palisade cells become more rounded towards the 

 interior and at the same time contain less chorophyll. Below 

 the epidermis and in the deeper layers there are numerous 

 sclerenchyma-cells which traverse the stem longitudinally; 

 in the older branch their lumen has almost disappeared. 



Ammodendron Conollyi Bge. (The Sand-Acacia). 



This species is found in the sand-desert and prefers 

 deep sand. It attains a height of 2 — 4 ( — 8) metres and is 

 a shrub (on the more stationary soils) or more frequently a 

 slender and in most cases a one-stemmed tree. The hairiness 

 of the leaves gives it a whitish grey appearance, the crown 



