198 

 A TAMARIX ASSOCIATION. 



P.Y 



William Burxs, B. Sc. (Edin.). 



{From the Botanical Laboratory of the Agricultural College, Poona.) 



In the uncultivated areas along the banks of the Nerbudda near Broach run 

 lines of tamarix. The zone occupied by this plant is comparatively narrow, but 

 it is often possible to distinguish two regions within the zone, of apparently 

 different ages, the older being higher up the banks. The tamarix is an orga- 

 nism well adapted to the conditions in which it occurs. These are sandy or 

 alluvial soil, saline water, and a lowlying but rather exposed situation. It has 

 been supposed that tamarix is rather a salt-plant than a sand-plant. How far 

 this is the case remains to be proved. In any case tamarix occurs where both 

 physical and physiological drought are imminent, and all its adaptations are 

 for resistance of drought. The roots are deep, the leaves are minute and 

 clasping, and on these leaves are peculiar impresso-punctate glands in which 

 salts accumulate. 



It is believed that the function of these deposits is to attract moisture 

 hygroscopically from the atmosphere and pass it on to the leaf tissue. In the 

 leaves of Tamarix articulata, according to Solereder, storage tracheitis occur 

 for the preservation of water. 



I was curious to know what other plants were associated with the tamarix 

 in its peculiar zone at Broach and so, in October 1909, 1 collected from a small 

 area (about 100 by 15 yards) all the plants I could find. Where the tamarix 

 grew it was the dominant plant, but the habit of the tamarix is not such as to 

 exclude the growth of other plants amongst it. The area I examined was of 

 recent growth and close to the water. The tamarix was from three to five 

 feet high and thickly planted, yet the slenderness of its branches permitted 

 sufficient air and light to enter for numerous subsidiary plants. In marked 

 contrast to the tamarix in this respect was Typha angustata, of which I found 

 one clump growing in a swampy, spot where no tamarix had rooted. This 

 Typha formed a compact and exclusive community, growing so close and 

 high that nothing else had a chance amongst it. 



Of tamarix I found three species, namely, Tamarix dioica, Tamarix articu- 

 lata and Tamarix ericoicles. These were all in flower and easily identified. 

 Tamarix ericoides has ten stamens, whilst the other two have five. Tamarix 

 dioica has unisexual flowers, whilst Tamarix articulata has hermaphrodite 

 flowers in interrupted spikes. Two other species are reported in Cooke's Flora 

 as occurring in Sind, namely, Tamarix gallica and Tamarix strieta ; but these 

 were not found in the Broach group. Tamarix gallica has five stamens like 

 Tamarix articulata, but has racemose panicles. Tamarix strieta has ten 

 etamens like Tamarix ericoides but differs in having the glands of the disc 

 passing into the bases of the staminal filaments instead of separating them. 

 Tamarix dioica and Tamarix articulata become tree-like in habit. Tamarix 



