197 



October. Being light and provided with wings it is easily 

 carried along by the wind. 



The leaves are centric in structure, of the type so often 

 described, with a palisade layer and a starch sheath towards 

 which the veins pass obliquely through the central aqueous 

 tissue. (See VOLKENS p. 138). The vein is surrounded by 

 sclerenchyma (fig. 39). 



Between the epidermis and the palisade cells is a layer 

 of cells with very thin walls and large intercellular spaces 

 (fig. 39 A and C). Some of them contain clusters of crystals, 

 also described and illustrated by VOLKENS (tab. XII, 3). 

 This crystal-layer appears to be distinct from the epidermis 

 but it may be compared with the corresponding one in Hal- 

 oxylon (WARMING 1897 p. 218). where it is included amongst 

 the epidermal tissues, and in both cases it may probably be 

 regarded as a hypoderm; there must be air between its cells. 



In var. longifolia the leaves are perfectly cylindrical; in 

 the stunted form they are often slightly concave or flat on 

 one side. 



Salsola subaphylla C. A. M. 



A shrub or small tree attaining a height of about 2 

 metres. It somewhat resembles the last species, but does 

 not attain the same height, its foliage is less dense, and it 

 sets fruit earlier. According to PALEZKIJ its life-period does 

 not at the most exceed four years, hence it is not employed 

 for sand-binding purposes. It is by preference a sand-plant 

 and attains its highest development where the sand is moving. 

 On clay or stony soil it appears as a small shrub of about 

 30 centimetres high. 



The leaves (fig. 13) are thick, cylindrical or half-cylindrical 

 and attain the length of about two centimetres. 



The year-shoots are branched, sometimes twice. The 

 distal parts of the year-shoots and branches are in the month 

 of July covered with flowers (fig. 13) subtended by scale-like 

 bracts; the fruit-bearing branches may be quite hidden 

 under the broad wings of the numerous fruits. 



After the cessation of the vegetative period the tips and 



