C4ENERAL REQUIREMENTS. 



which are necessary to carry on the vital functions of the plant. 

 Plants which develop no root-hairs seem to absorb sufficient 

 water and salts for their needs through cells non-protuberant 

 from the main surface of the roots. Root-hairs greatly increase 

 the root's absorbing surface. Some writers (see Kerner and 

 Oliver " Natural History of Plants," Volume I, page 91 and 

 others) lead us to understand that root-hairs are absent in the 

 case of the date palm. I may, therefore, mention that root-hairs 

 have been found on the roots of date palms in the case of plants 

 growing in well drained soil at Lyallpur where the permanent 

 water-level is at about 80 feet depth ; at Mazuffargarh at a depth 

 of 8-| feet where the subsoil water-level during most of the year 

 is 7 feet or less from the soil surface but which at the time of 

 examination was. at 9 feet depth ; and elsewhere. 



Root-hairs are also found on the rice plant. 



In the peripheral (extrastelar) region of the root of the date 

 palm numerous bands of sclerenchyma (fibrous tissue strengthened 

 and toughened by the deposit of a substance called lignin) are 

 developed, which together with the sclerenchymatous tissue in 

 the central portion of the root give to that organ great tensile 

 strength a character most important when the date tree has 

 to hold itself erect against the force of the fierce winds that 

 sometimes sweep through desert regions. 



A date tree planted as a sucker at Lyallpur five years 

 previously was found to possess approximately 350 secondary 

 roots. The longest of these roots was about 18 feet in length 

 and was one of those which started from the stem most near the 

 surface of the soil. It left the stem at an angle of less than 20 

 degrees to the horizon, and bent sharply down into the soil when 

 about 9 feet away, so that its tip was only about 13 feet from 

 the tree. 



Several other roots near the soil surface described a similar 

 course. The great mass of the roots, however, when they started 

 from the tree descended at a very sharp angle (see illustration 

 No. 1, page XIX) and ended within a radius of 6 feet from the 



