3 i 4 BRITISH FOREST TREES 



best be cut away at once in the next thinning. During 

 the later stages of growth it is equally light-demanding 

 with the birch and larch, and but for its small value as 

 timber, it would be well suited to be grown as standards 

 over coppice. 



Attainment of Maturity and Reproductive Capacity. The 

 aspen soon gets unsound in the bole, which perhaps arises 

 from the fact that most of those to be found in the forests 

 are probably survivals of stoles or root-suckers that have 

 shot up with greater rapidity than the seedlings which they 

 have suppressed. In consequence of this, it cannot sustain 

 the usual rotation of hardwoods, and has to be cut out 

 early, before it can possibly yield much outturn in timber 

 for technical purposes. Such sucker-grown stems are 

 usually thinned out before they attain an age of forty 

 years. Some of the poplars reach their physical maturity 

 at about sixty to eighty years, but can under favourable 

 circumstances maintain themselves up to a hundred years, 

 before exhibiting the usual signs of over-maturity and 

 senile decay. 



The Salicacece are dioecious, and the male individuals 

 vastly outnumber those that are of the female gender ; the 

 Italian or pyramidal poplar produces only male flowers in 

 Europe (it is indigenous to Taurus and the Himalayas, 

 where Royle found both the male and the female trees), 

 and must therefore be propagated by slips or suckers. But 

 when male and female-flowering individuals find themselves 

 in close proximity, the formation of seed begins early and 

 continues freely, almost annually. It ripens and scatters 

 early in June, and though unwinged, can be wafted long 

 distances owing to the downy filaments arojund it. It is 

 exceedingly small and light, germinates within a week after 

 falling, and loses a good deal of its germinative power if 

 gathered and kept even for a day or two, so that artificial 



