40 THE JOUENAL OP INDIAN BOTANY. 



46. Flaveria contrayerba Pers — Not common ; not in a good 

 condition. 



47. Evolvulus alsinoides L— Rather common in poor soils. 



48. Lippia nodiflora Michx.— Not very common. 



49. Achyranthes aspera L.— Not very common. A very hairy 

 plant. 



50. ABrua javanica Juss. — Not very common. A very hairy 

 plant. 



51. Aristolochia bracteata Betz. — Occasional. 



GRASSES. 



52. Pennisetum Alopecuros Ness. 



53. Ischaemum pilosum Hack. — Very common in black soil 

 fields where it shows large dry patches which were dug up and fed to 

 cattle. 



54. Andropogon pertusus Willd. 



55. Andropogon annulatus Forsk. 



56. Cynodon dactylon Pers.— Found green only near moist 

 places from where they were dug up and fed to cattle. 



All these grasses dry up in the absence of water but sprout again 

 when it is available. 



When we try to consider the points brought out by the above 

 observations the first thing noticed is that according to the nature of 

 the soil the amount of available moisture varies roughly from 1-4 per 

 cent, during the hottest and driest part of the year. In the sands the 

 available moisture was under 1 per cent. In the course 'murum' soils 

 it was between 1 and 2 per cent. In the black soils with their 

 very large amount of clay the available water even at this time rose to 

 between 3 and 4 per eent. This seems to be the limit of growth of any 

 phanerogamic vegetation whatever on these various classes of land. 



A general reduction in the size of the plant and of its aerial parts 

 such as branches, leaves, &c. and the development of a tap root (diagrams 

 of some of the typical roots are attached) were characteristic, though 

 the latter was not quite universal. There are two dicotyledons in the 

 list which even under the very highly xerophytic conditions did not 

 show an appreciable tap root. The first of these is Tragia cannabina 

 L. and the second Garalluma fimbriata Wall. The primary root of 

 the former of these seems to have been soon divided into several 

 secondary branches. These branches are long and rather stout how- 

 ever, and descend obliquely into the soil so that they can perform the 

 same function as a tap root. This plant is moreover well supplied 

 with other means of decreasing transpiration andhence economising 



