452 XXIII. LEGUMINOSAE 



Under favourable conditions the growth of the seedling is rapid from the 

 commencement, plants regularly weeded and watered attaining a height ol 

 3 ft. or more in three months from germination. Branching takes place at 

 an early age, and the general habit is more or less straggling. The seedling 

 develops a long taproot, which may attain a length of 2 ft. or more in three 

 months. 



Under natural conditions the growth of the seedlings may be extremely 



slow, particularly if they are hampered by weeds or subject to damage by 



grazing. Thus a plot of natural seedhngs 200 sq. ft. in area on sand and 



shingle among scattered tufts of grass about 3 ft. high in a dry river-bed in 



the Siwaliks was kept under observation for about 4| years : the following 



shows the number of seedlings counted and their maximum height at different 



stages : 



No. of seedlings 

 Date of observation. present. 



December 11, 1910 (end of 1st season) . . . 201 



December 28, 1911 (end of 2nd season) . . 



December 19, 1913 (end of 4th season) ... 74 



April 14, 1915 (beginning of 6th season) . . 24 



These results show a steady diminution in the number of seedlings and no 

 progress in their growth, this being due mainly to damage by grazing ; nearly 

 all the survivors were found in the clumps of grass, where they received 

 a certain amount of protection. 



The beneficial results of irrigation and weeding, of which the latter is of 

 even more importance than the former, are well demonstrated by the following 

 figures showing the development of seedlings in various experimental plots 

 at Dehra Dun : 



Acacia Catechu : development of seedlings under varying treatment. 



Time of ob- Irrigated. Unirrigated. ^ 



servation. j^pg^^jarfy weeded. Not weeded. Regularly weeded. Not weeded. 



ft. in. ft. 



End of 1st Maximum height Maximum height (1) Maximum height 8 (1) Maximum height 

 season ry ft. 2 in. 5 in. (fairly vigorous) (very weakly) 



(very vigorous) (weakly) 



^ (2) ,. 3 8 (2) 



(3) 2 3 (3) 



End of 2nd Maximum height Maximum height (1) ,, ,, 4 (1) ,, 



season 10 ft. 3 in. 1 ft. in. (2) 6 3 (2) 1 



(very vigorous) (3) ,, ,, 12 9(3) ,, ,, 1 



(4) 12 (4) 1 



(5) 10 (5) 2 



Endof 3rd Maximum height Maximum height (1) 9 6 (1) Height 2 ft. 6 in. to 7 



season 14 ft. in. 1 ft. 1 in. (2) Maximum height 18 8 thin lanky stems am 



(very vigorous) Mean height 8 4 growth of weeds 



Maximum girth 7 



(3) Maximum height 14 10 



(4) Maximum height 17 9 

 Mean height 6 

 Maximum girth 7J 



In most of the unweeded plots the seedlings were all killed out by suppression 

 or had damped off before the end of the third season. One of the commonest 

 forms of mortality in the case of seedlings in a heavy growth of weeds is the 



