ACACIA 451 



leaves, and add to the beauty of the trees. The trees continue in flower until 

 July or August, sometimes later. The pods develop rapidly, becoming full- 

 sized by September or October, and turning from green to reddish green and 

 then to brown : they begin to ripen by the end of November and continue 

 ripening during December and early January. The pods (Fig. 170, a) are 

 2-4 in. long by 0-4-0-6 in. broad, straight, flat, dark brown, shining, dehiscent, 

 usually three- to six-seeded. The seeds (Fig. 170, b) are 0-25-0-35 in. by 

 0-2-0-3 in., broadly ovate or orbicular, dark greenish brown, smooth, shining, 

 moderately hard, with a hard testa which becomes soft and pliant on soaking. 

 About 900-1,100 seeds weigh 1 oz. 



The pods dehisce not long after ripening, and commence falling in January, 

 continuing to fall in the succeeding months : the seeds adhere to the pod 

 valves, and the latter being light are often blown to a considerable distance 

 from the trees, dissemination of the seed being effected in this way. In alluvial 

 tracts the dissemination of the seed is further effected by water. Some pods 

 remain on the tree until the following October, by which time, however, the 

 seed has become so damaged by insects as to be useless. 



As a rule the tree seeds well every year. The seed can best be collected 

 by stripping the pods off the trees in December or early January and spreading 

 them in the sun for a few days. The seeds cling tenaciously to the pod valves, 

 and in order to detach them it is necessary to heap the pods on a large cloth 

 and beat them well with sticks, after which the seeds can be separated by 

 shaking and winnowing in a flat basket. 



The seed is badly subject to insect attacks, even when carefully stored. 

 Seed kept for one year was tested at Dehra Dun and found to be quite unfertile : 

 it is not certain how far this was due to insect attacks. It is advisable, there- 

 fore, to sow the seed the year in which it is collected. The fertility of fresh 

 undamaged seed is high. The seed germinates readily with moderate rain, 

 and requires no special preparation to stimulate germination. 

 ^ Germination (Fig. 170, c-g). Epigeous. The radicle emerges first and 

 curves downwards ; the hypocotyl then elongates, with or without arching, 

 and raises above ground the cotyledons enveloped by the testa. The cotyledons 

 expand, turning from yellow to pale green, and the testa falls to the ground. 



The seedling (Fig. 170). 



Roots : primary root long, wiry, thickening considerably after a few 

 months, terete, tapering, whitish or pale brown becoming darker brown : 

 lateral roots few to numerous, short, fibrous or wiry, distributed down main 

 root : nodules present. Hypocotyl distinct from root, 0-5-0-8 in. long, terete, 

 expanded in a ring at the base, white becoming green, glabrous or sparsely 

 pubescent in upper part. Cotyledons very shortly petiolate, plano-convex, 

 somewhat fleshy, 0-3-0-4 in. in diameter, orbicular, entire, base sagittate, 

 glabrous, yellow becoming green, obscurely 3-veined. Stem erect, somewhat 

 zigzag at the nodes, thin, delicate at first, becoming wiry, green or reddish, 

 young parts pubescent, elsewhere glabrous or nearly so. Leaves alternate. 

 Stipules minute, subulate, caducous. First leaf once paripinnate with three 

 to four pairs of opposite leaflets 0-2-0-25 in. by 0-1 in., rachis pubescent ; 

 subsequent leaves bipinnate, at flrst with one pair, then with two pairs of 

 pinnae, each pinna at first with 3-5 pairs of leaflets, the number increasing 

 with succeeding leaves, leaflets 0-2-0-4 in. by 0- 1-0-2 in. ; the number of 

 pinnae increases in subsequent leaves. 



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