212 G.ORSHAN 



(e) Artemisia monosperma. The life cycle of this plant is similar to that of 

 A. herha alba with one difference, that doUchoblasts develop not only from 

 the base of older dohchoblasts, but also from their upper portions. 



(f) Noea mucronata. The dohchoblasts start growing from renewal buds 

 in November. Their growth reaches its maximum rate in spring. These 

 branches bear larger linear leaves which are gradually shed in an acropetal 

 direction from the middle of May to the beginning of July. Meanwhile 

 (from the middle of May to August) thorny brachyblasts develop bearing 

 scale-hke smaller summer leaves from the axillary buds at the upper part of 

 these dohchoblasts. The flowers appear on the brachyblasts by September 

 and the plant sets fruit during October and November. 



During the winter and the next summer the upper portions of the 

 dohchoblasts as well as all the brachyblasts die back while the renewal 

 buds appear in the autumn on their lower portion or on older stems. 



(g) ZygophyUum dumosnm. This plant differs from those already described 

 in that there is no summer growing season and the two types of branches 

 develop and grow almost simultaneously. All the leaves are of the same 

 type. 



The renewal buds are developed on the lower parts of the dohchoblasts 

 immediately after the first effective rains. The brachyblasts develop almost 

 immediately from the axils of the leaves of the dohchoblasts. The flowers 

 which appear a short time after the onset of growth are born on the 

 dohchoblasts. The plant sets its fruit early in summer. 



Surface reduction takes place mainly through the shedding of the double 

 laminae which starts at about May and goes on gradually through the early 

 summer. During the late summer the succulent petioles alone form the 

 only leaf cover of the plant. They are also gradually shed with the increase 

 of water shortage. 



(h) Anabasis articulata. This plant is an articulate stem succulent bearing 

 no leaves. Its dohchoblasts develop in winter after the first rains from renewal 

 buds situated at the lower part of the plant. They reach their maximal 

 length (which is generally about 10-20 cm) in March. From March to May 

 lateral brachyblasts distinguished from the dohchoblasts by their shorter 

 intemodes develop on them and later in October bear the flowers. The 

 plant sets fruit in November and December. 



Instead of leaf shedding, which is typical of the non-articulate chaema- 

 phytes, the green cortex oi^ Anabasis starts dying back, becoming yellow in 

 an acropetal direction from May onwards. Cracks appear in it on stems older 

 than one year and later it is shed. 



Apart from the drying and shedding of the green cortex, the transpiring 



