ALBIZZIA 469 



at Dehra Dun showed that the seed retains its vitality well for at least one 

 year, though fresh seed has a higher percentage of fertility than seed which 

 has been kept for a time ; seed kept for a year germinated more rapidly than 

 fresh seed. The seeds are very subject to the attacks of insects, particularly 

 of a small whitish caterpillar, and many are destroyed both on the tree and 

 on the ground. Rain sometimes causes much of the seed to rot in the pods, 

 particularly after they have fallen, and it is therefore advisable to collect the 

 seed as soon after it ripens as possible. This can best be done by men ascending 

 the trees and picking the pods off, or by knocking them off with the aid of 

 a long stick ; in the latter case it is advisable to spread sheets under the trees, 

 as much of the seed may fall out during the process. The seeds are extracted 

 from the pods either by opening the latter or by crushing them in the hands 

 and separating the seeds by winnowing. 



Germination (Fig. 178, b-d). Epigeous. The radicle emerges first, and 

 the hypocotyl elongates by arching, soon straightening and carrying the 

 cotyledons above ground ; as a rule the testa is carried up over the cotyledons, 

 falling with their expansion, but sometimes it remains underground. 



The seedling (Fig. 178). 



Roots : primary root long, terete, tapering, wiry, brown : lateral roots 

 moderate in number, short, fibrous, distributed down main root : nodules 

 present. Hypocotyl distinct from root, 1-5-2 in. long, terete, tapering upwards, 

 minutely pubescent. Cotyledons sessile, 0-6 by 0-4 in., elliptical ovate, apex 

 rounded, base sagittate, flat or slightly plano-convex, fleshy, entire, green, 

 glabrous. Stetn erect, terete, wiry, green, pubescent ; internodes 0- 1-0-5 in. 

 long. Leaves alternate. Stipules minute, lanceolate. First leaf once pari- 

 pinnate, rachis 0-6-1-3 in. long, leaflets opposite, five or six pairs, 0-4-0-7 in. by 

 0-15-0-17 in., obliquely oblong, subsequent leaves bipinnate, at first with one 

 pair of pinnae 0-7-1-5 in. long, common rachis 0-5-1 in. long, the number of 

 pairs of pinnae increasing subsequently. 



The development of the seedling varies greatly among individual plants 

 even under identical conditions, but there are certain factors which stimulate 

 development, and which induce remarkably rapid growth from the com- 

 mencement ; the most important factors are absence of weeds, loose soil, 

 sufficient soil moisture, and full sunlight. Numerous experimental plots at 

 Dehra Dun have demonstrated the marked effect of regular weeding and 

 loosening of the soil on the growth of the seedling, and although watering 

 has a beneficial effect it is of comparatively little avail unless weeding is 

 carried out. 



As regards light requirements, experimental plots of seedlings grown 

 under shade of varying intensity have shown that dense shade greatly retards 

 germination, some seed failing to germinate until the second year ; seedlings 

 which do appear are capable of standing heavy shade for one season but 

 not longer, and development is very slow, a maximum height of only 4 in: 

 having been recorded at the end of the season. The seedlings develop 

 satisfactorily with moderate side shade, but at Dehra Dun their growth was 

 found to be inferior to that of plants grown in full sunlight. The following 

 measurements recorded in various experimental plots at Dehra Dun exhibit 

 the marked effects of regular weeding, whether accompanied by irrigation 

 or not : 



