TEE FLORA OF THE IKDIAS DESERT. 



509 



An order of some importance for the process of sand-binding is the Cmerace^ 

 some of the stolom erous members of which are able to arresl the advarfce 3 a 

 dime more effectively than any other group of plants observed bv us. On P^te 



f W of' PI. iT ^ ?^ '^' T''™ ''"P^ °* '^' "°^^^^ ^^d of the dune 3 rlt 

 S W of Phalodi mentioned above. The slope is covered by a dense niarof 

 Cyperus arenarius A similar case is represented in Plate XXIV- 4 where a 

 struggle between the same plant and the dune, on the le.side (NE-slope) 'of which 

 it grows, can be plainly distinguished. The dune has, probablv early in the 

 ramy season, made an attempt to destroy the plant family, but'failed so that 

 now the plant has again mounted to the dune crest by means of long stolons 

 We never observed this species to the windward of a dune : but once a familv" 

 had established Itself on the E-NE-slopes, no other plant seemed to have I 

 chance of invadmg the same locahty. 



Among the commonest sand grasses we note several species of Emqrostis 

 Most conspicuous among these is E. tremula, a very beautiful grass, which was 

 observed at its best at Osian. E. ciliaris is also common, preferably on moist 

 sand. Cenchrus catharticus is another common grass, which does not escape 

 notice, owing to its method of seed dispersion. The small spikelets have curved 

 awns, thus readily sticking to the clothes of man or the coat of animals, and 

 being very difficult to remove. We have seen sheep so covered with these 

 spikelets that the animals had to be shorn. Pennisetum prieurii has a very 

 similar habit to that of the last plant, but the spikelets lack the curved awns. 

 P. cenchroides al;o grows on sand. End is common all over the region. 



Having now described the general aspect of the sand formation, we add a 

 few details from our notes. 



The sandy plains round Jodhpur( (Plate XVII) have already been mentioned. 

 They extend towards Mandor (Plate VI-A.) and have throughout a very uniform 

 vegetation with Crotalaria burliia as predominant jjlant. On the plain north 

 of Balarwa Calotropis procera, Crotalaria burliia and Indigofera ovaliflia are 

 uniformly distributed, while here and there occur clumps of Capparisdecidua. 

 Between Balarwa and Osian we have first a plain with Capparis, etc., later dune 

 sand. The most conspicuous feature of the vegetation at the time of our visit 

 was here the abundance of a large Compositous plant, Avith yellow flowers, 

 Pulicaria tvightiana, which associates with Crotalaria, Aerua, etc. Round 

 Osian there are a number of low dunes, from which two views taken close to the 

 railway station are shown on Plate XX. The following plants are the commonest: 

 Leptadenia spartium, Zizy2Jhus rotundifolia, Capparis decidua, Panicum tur- 

 gidiim, Cenchrus catharticus, Arnebia hispidissima. The presence of a number of 

 tolerably large shrubs indicates a greater age of these dunes. We noted that 

 Leptadenia spartium here had a distinct stem, supporting a fairly large crown, a 

 habit quite different from that of the shrubby plants, branched from the base, 

 invariably observed nearer to Jodhpur (Plate XVI). The abundance of 

 Calligonum on the Bhikamkor dunes has already been referred to. In this place, 

 Cenchrus catharticus and Citrullus colocynthis were also common, while Crotalaria 

 burhia and Indigofera ovalifolia, as well as Leptadenia were far less common 

 than usual. These dunes made the impression of being of a comparatively recent 

 date. We noticed here that the dune sand becomes quite firm when wet and may 

 even support the weight of a man. A short distance W of Bhikamkor there are 

 other dunes without Calligonum, but with numerous Lycium barbarian. Here 

 Sericostoma pauciflora is also common and reaches an unusual size, up to two 

 feet in height and three or four feet across. Blepharis sindica also occurred in 

 unusually large specimens. In addition, the following plants were particularly 

 noticeable : Farsetia jacquemontiana, Boerhavia diffusa, and the grasses Anslida 

 funiculata, A. adscencionis, Cenchrus catharticus, Panicum turgidum. 



Having lost much time at Bhikamkor, we determined not to halt at any other 



