The tall bush which you can see on the right hand edge of the featured photo is called phog in Hindi, and Calligonum polygonoides by botanists. Other clumps can be seen on further dunes. Each thicket can grow about as tall as a human, and spreads out in a circle. Unfortunately, I visited the Thar desert in winter, when one does not get to see the flower or berries of the phog. The flowers and buds are eaten as a raita, the shoot is used as feed for livestock and the root is used to make charcoal. The deep tap roots and lateral root system together contain a larger biomass than shoots.
As you can see from this panoramic shot, the plant grows very well in the extremely arid habitat of dunes where little else grows. As a result, it serves to stabilize the dunes. Over-exploitation of the plant to produce charcoal used by goldsmiths and local ironsmiths has begun to endanger the phog. There are attempts to propagate the plant through cultivation and replanting, but this has not been uniformly successful. Studies of competition between the phog and other varieties of desert grass shows that in more moist conditions the phog loses out. Consistent with this is the fact that growth of C. polygonoides changes soil properties less than other plants do.
Of more than 80 species of Calligonum recorded worldwide in arid areas of southern Europe, northern Africa, west and central Asia, only this one species grows in the Thar desert of India. A recent study found very high degree of genetic diversity in the phog population in Rajasthan. However, there was no geographical clustering of varieties. When I talked to an expert, I was told that the confused state of this first study makes this subject worth a second look. After reading the scant literature on this plant, I would be willing to do such a study if I had the expertise and the means.