- 99 — 



undershrub with an offensive smell ; Artemisia, an undershrub, 

 and Peganum Harmala one of the Zygophyllaceae with a 

 thick tap-root and prostrate branches. These species are all 

 xerophytic in structure, but at the same time somewhat 

 mesophytic since they are all comparatively leafy. The fol- 

 lowing species occurring in the lower sandy basins are halo- 

 phytic in structure. Cressa cretica, a geophyte with salt-excret- 

 ing leaves, Zijgophyllum-species with thick leaves, Tetradiclis 

 tenella, Halimocnemis-species, Halanthium gamocarpum and 

 Lipskii, Salsola crassa, spissa, sclerantha, Halostachgs caspica 

 and Euphorbia Turczaninowii, the latter with thick glabrous 

 foliage. Most of these are annuals (summer-annuals); Cressa, 

 Zygophyllum and Halostachijs are perennials. All except 

 Cressa are stem-succulents, leaf-succulents or bracteole-succul- 

 ents. Some are the same species met with in the clay- 

 desert, and they all belong to the same types seen there. 

 The lower saline parts of the Hummock-desert are thus very 

 closely related to the clay-desert, as regards their vegetation; 

 the two are scarcely distinguishable except by the soil. 



In this connection we may quote a description by Radde 

 (1. c. p. 154) of the sand-areas near the border of Afghanistan 

 (July 8'"): 



"Diese alten festen Sandberge ernahren keine Strauch- 

 art welche auf dem jiingeren zumteil noch wogenden Sande 

 die ersten Bedingungen zum Haften desselben darbieten. 

 Nur wo entblosster, beweglicher Sand lagert, finde ich 

 wenige, schwachliche Exemplare von Calligonum polygo- 

 noides PalP). Auf der ganzen Strecke sahen wir meistens 

 eine Unterlage von jetzt vollstandig vergilbter Poa bulbosa, 

 welche die Pferde dennoch gerne fressen. Alhagi Camelo- 

 rum, typisch und in einer niederliegenden Varietat in grau- 

 griinen Kolorit wechselt mit Peganum Harmala ab. Beide 

 bevorzugen den mehr lockeren Sandboden, auf dem alten 

 festen werden sie schwacher und seltener, diesen liebt Pro- 

 sopis Stephaniana, weite Strecken sind von ihm bestanden, 

 dazwischen etwas Heliotropium dasycarpum und uberall 

 gelbes Delphinium camptocarpum, welches von der Sonne 



'} C. Pallasia I'H^r. O. P. 



