GEEGABIOUSNESS AND SOCIABILITY OF SPECIES. 101 



(A) The generally mild nature of night-frosts at the high situa- 

 tions where the tree is gregarious. This circumstance combined 

 •with the extraordinary thickness of its young shoots, the nature 

 of its bark and sap alluded to under {g), and the shedding of its 

 leaves at the beginning of the cold weather, enables the tree, which 

 would otherwise be very sensitive, to progress upwards in spite of 

 frost. 



{{) Its singularly great resistance to the effects of conflagra- 

 tions, thanks principally to the nature of its bark, to its being out 

 of leaf during the season of fires, to the vigour of its dormant buds, 

 to characters (c) and {d), to its remarkably accommodating nature 

 in respect of the quaUty of the soil, and to the spareness of the 

 combustible undergrowth on the ground. 



{j) The very low value set on its wood as timber and even as 

 fuel, it being almost the last tree to be cut for export. 



Hardwickia binata. 



This is a tree of the dry tracts of Central and Southern India, 

 but is also met with along the foot of the Kaimur Hills from 

 Eewah to Hazaribagh. It is confined to strongly siHcious soils, 

 whatever their origin, and attains its finest dimensions on rocky 

 rugged ground, even where there is scarcely a vestige of soil. It 

 sometimes forms pure forests, but oftener occurs as a top-story over 

 an open undergrowth of Anogeissus latifolia, BoswelUa, khair, teak, 

 &c. The causes which combine to make it gregarious are — 



(a) The dryness and poverty of the soils which it affects and in 

 which its few large companions do not develop their highest vigour. 



Qj) Its extremely profuse general seeding once in three or four 

 years. 



(c) The easy dissemination of its seed to several hundred feet 

 from the parent tree, thanks to the flat light pod, which contains 

 only a single seed and generally dehisces only after it has fallen. 



(d) The great facility with which the seed germinates. 



(e) The remarkable length of taproot developed by its young 

 seedlings, which circumstance, besides securing for them many other 

 important advantages, enables them to grow in the midst of dense 

 grass. 



(/) The persistence of its foliage during at least ten and a half 

 months out of the twelve. 



(y) Its producing more than one flush of foliage during the 

 year, each accompanied with a vigorous development of new shoots. 



