214 



pliant and more or less pendulous; in clay-desert species 

 on the contrary they are generally stiff and short. 



The year-shoots are branched except in a very few cases 

 (Halimodendron, Reaumuria oxiana). Branched year-shoots 

 are thus the rule, and non-branching the exception. A similar 

 case has, to my knowledge, never been pointed out for any 

 community of Fanerophytes. 



WARMING (1892, pp. 408, 252) and after him MALME have 

 drawn attention to a number of South American species with 

 branched year-shoots. RACIBORSKI also gives illustrations of 

 several species of this kind, but without recording this 

 characteristic. These species are mostly forest-plants, but 

 some belong to the Savannas (MALME). MALME regards the 

 branched year-shoot as a primitive character in dicotyledonous 

 trees, non-branching on the contrary being a secondary fea- 

 ture acquired in the course of time. However this condition 

 in the case of the broad-leaved South American plants is of 

 less interest to us than the branch system in other Fanero- 

 phytes poor in leaves or leafless. This condition is certainly 

 worthy of special study although in the literature I have only 

 found occasional references to it. 



In many cases the year - shoot branches are annual 

 assimilating shoots, more rarely they are continuation shoots 

 which take part in the extension of branches. No definite 

 limit can be drawn however between the two. The assimi- 

 lating branches have been described in many of the species 

 mentioned (e. g. Eremosparton, Calligonum, Tamarix, Astra- 

 galus, Salsola etc.); biologically they play the part of leaves. 



Assimilating branches in many species are not confined 

 to the last year-shoot, but also occur on older branches. In such 

 cases they arise on the exterior side of lateral branches, or where 

 such ones have previously been, and often several together. Thus 

 the characteristic tufts of branches originate, which likewise 

 distinguish so many of the trees and shrubs of the desert; 

 they have been described and illustrated in the case of several 

 species (e. g. Eremosparton, Calligonum^ Smirnowia). Similar 

 conditions are also found in Spartium, Carmichaelia, and others. 



A further characteristic of the year-shoots is, that they 

 do not as a rule persist throughout their whole length, but 



