213 - 



in T. hispida. All the cells of the single-layered epidermis 

 are distinctly convex and papilla-like. The stomata on the 

 upper and lower surfaces, and the salt-glands are sunk. One 

 layer of palisade cells all round is present both in the leaves 

 and the assimilating branches. The leaf also has rather open 

 spongy parenchyma and veins with a bast-sheath besides 

 storage-tracheids ("Speichertrachei'den"). 



I have not investigated in detail the more mesophytic 

 fanerophytes (Elaeagnns, Ulmm, Morns, Popnlus, Salix). 

 Elaeagnns hortensis was observed in August with two series 

 of branches on the year-shoot, but this does not appear to 

 be the rule. The same holds good with regard to Salix 

 angnstifolia. The species of all the genera just mentioned 

 flower in spring. 



The above Fanerophytes have the following characteristics 

 common to all or some of them. 



The leaves are greatly reduced. In one set of species 

 they take no part as assimilating organs (Eremosparlon, Calli- 

 gonnm, Ephedra, Haloxylon, Halostachys, Halocnemnm], while 

 in others they are scale-like, but green (Tamarix, Reaumnria 

 fruticosa). Astragalus has leaves which are wholly or partly 

 shed during summer, but whether as in the case of Spartinm 

 jnnceiim (according to BERGEN), there is no assimilation or 

 at any rate very little after the leaves are shed, I cannot 

 say, and one can scarcely draw a conclusion from a single 

 case. Ammodendron, Halimodendron and Smirnowia have 

 persistent, small, hairy leaves, while Prosopis, Atraphaxis, 

 Lyciiim, Nitraria and Reaumnria oxiana have persistent small 

 and glabrous leaves. The Salsola species have cylindrical 

 persistent leaves. 



The leaves in Salsola and the assimilating shoots in the 

 leafless species are all centric in structure, the latter in most 

 cases have abundant mechanical tissue. 



In the flat -leaved species the leaves are without excep- 

 tion isolateral in structure. 



The branches in most sand-desert species are slender, 



