THE FLORA OF THE INDIAN DESERT. 511 



Panicum turgidum, Elionurns hirsutus, Pennisetum cenchroides, Andropooon 

 vwarancusa, all large and tufted, associated with Aerua pseudo-tomentosa Ld 

 Clerodendron phlomidis. On the low dunes met with further on, Rhunchosia 

 arenana was common. Zizyphus rotundifolia abounds, but prefers gravelly soil 

 (Plate XXm-A.). The dunes then become almost covered with Haloxylon 

 mhcornicum, a plant observed only in this neighbourhood. Although abundant 

 on sand, it reaches its best development on gravel, and it will be referred to 

 later under the corresponding formation. It associates with Orotalaria hurhia 

 and Aerua tomentosa. Capparis decidua now becomes more common, Zizyphus 

 less so. The .4eri<a-association met with near Sodakoer village 'has~ been 

 described above. It is surrounded by a belt of Haloxylon, showing dark in 

 the distance to the right on Plate XXII -A. Hardly any notes were taken of 

 the vegetation along the road from Sodakoer to Jaisalmer. The most notice- 

 able feature was perhaps the local abundance of Cassia obovata on a few dunes 

 about half way. 



Some characteristic dune associations near Jaisalmer have been described 

 above. The sandy plains were here very similar to those round Jodphur, 

 Crotalaria burhia predominating (see Plate XXXII-B., XXXIII). 



Between Jaisalmer and Devikot Cenchrus catharticus is common everywhere 

 on sandy soil, but has here a more prostrate habit than in the east. On the 

 Devikot sands, Lycium barbarum is conspicuous and often associated with 

 Capparis decidua and Panicum antidotale (Plate XVIII-A.). About three miles 

 south of Devikot a range of dunes is passed which show many bare, wind- 

 swept slopes with shifting sand, but which are generally covered by Crotalaria, 

 etc. Clerodendron is common among these dunes, and there are large tufts of 

 Panicum antidotale. Daemia extensa is often found climbing on the larger shrubby 

 plants. Nearer to Vinjorai village, Callingonum and Leptadenia grow on dunes. 

 On the sandy plain SE of the village the vegetation consists of Zizyphus and 

 Prosopis, Eleusine sp., Elionurus hirsutus and other grasses, several species 

 of Heliotroinum, Mimosa hamata and Indigojera ovalifolia. The two species 

 of Aerua are not common here. Below Kotda hill Calligonum occurs on sandy 

 ground together with a few Aerua famiUes and the grasses Panicum turgidum, 

 Elionurus hirsutus, Pennisetum cenchroides. On the hill itself a small dune 

 has accumulated on which, curiously enough, Euphorbia neriifolia has been 

 able to estabhsh itself. To show how a small dune in a fairly sheltered spot 

 may be invaded by a variety of plants, we give the following hst of species 

 observed here : Calligonum, Lycium, Capparis, Sericosioma, Crotalaria burhia 

 Aerua pseudo-tomentosa, Tephrosia sp., Calotropis, Indigofera argentea, Citrullus 

 colocynthis, Cyperus arenarius, Cenchrus catharticus, Panicum turgidum. 



Along a sandy dried up river bed at Barmer, Cadaba indica and Sahadora 

 oleoides abound. They are associated with Euphorbia neriijolia, Commiiihora, 

 Panicum antidotale, etc. 



Throughout the region, on sufficiently firm, sandy soil, a few pecuUar species 

 of fungi were common. The specimens collected have not yet been determined. 



Gravel Formation. 



We group under the above heading the associations pecuhar to the coarser 

 type of sand, or gravel, covering large areas in our region. The fairly sharp 

 distinction between sand and gravel is probably due to the sorting action of the 

 wind, which picks up and transports the grains of the former, deposituig them 

 finally in dunes, but which cannot move the pebbles of the latter to any large 



Plate XIV- A., taken from an elevated point east of Loharld, gives a good idea 

 of the dreary monotony of a gravel plain. The intervals between the gra%e 

 pebbles are large enough to allow the scanty rain water to escape, and with it 

 any chance particles of humus carried to the spot by the wmd. Ihe difference 



