CHAP. cm.

J'ALICA CEA3. PO PULUS.

1641

1503

older branches is grey. In the beginning of April, themale catkins, which are generally about 3 in. in length,appear; and, about a week afterwards, the female catkins,which are shorter, come forth : a week after the expan-sion of the flowers of the female catkins, the males dropoff; and, in five or six weeks afterwards, the seeds wildhave ripened and dropped also. The seeds are enclosedin a hairy or cottony covering; in consequence of which,they are wafted to a great distance by the wind. Thegrowth of all the varieties is extremely rapid; so that atree, 10 years planted, in soil moderately good andmoist, will attain the height of 30 ft., or upwards, witha trank from 6in. to 9in. in diameter; as has been thecase with several trees in the Horticultural Society’sGarden. As a proof of the rapidity of the growth ofthe abele tree, Evelyn mentions one of these trees atSyon, “ which, being lopped in February, 1651, did, bythe end of October, 1652, produce branches as big asa man’s wrist, and 17 ft. in height.” Truncheons of the white poplar, 9 ft.long, planted on the banks of a stream, some yards from the current, had, in12 years, trunks nearly 10 in. in diameter; and had heads in proportion. ( BathSoc. Papers, 1786, vol. iii. p. 90.) The duration of the tree rarely exceedstwo centuries; but, when it is to be cut down for timber, it should be seldomallowed to exceed 50 years’ growth, as the heart-wood at that period, on mostsoils, begins to decay. Mitchell says that, on the banks of rivers, the tree isat its full value in 40 or 50 years; but that, in dry situations, it will requirefrom 50 to 70 years to mature it. ( Dendrologia , &c., p. 51.) In the Dictionnairedes Eaux et Forets, it is stated, that a tree planted in a field, and surroundedby a fence at 25 ft. distance from it on every side, formed by its suckers, in20 years, a circular clump of wood 50 ft. in diameter; and, consequently,that 30 or 40 trees would cover an acre with a thick wood in the same spaceof time. Hence it follows, that, when the tree is once introduced into woods,especially where the soil is loamy and moist, it forms a perpetual successionof young trees, however frequently these may be cut down. When treatedas coppice-wood, the abele is by no means a durable plant; the stools decay-ing after they have borne three, or at most four, crops of poles.

Geography. The common grey poplar (P. (a) canescens) is generally sup-posed to be a native of Britain, as well as of France and Germany; but theabele tree (P. alba) is thought by some to have been first brought to Englandfrom Flanders. This we think highly probable; and it is favourable to ouropinion that P. alba and its varieties ought to be considered as cultivatedforms of P. canescens. P. alba and P. (a.) canescens are indigenous to Europe,as far north as 56° or 57° ; and they are found throughout the south of Eu-rope, Caucasus, Persia, and Barbary. They grow in most districts of Britain;and a few stunted plants of P. alba are said by M'Culloch to comprise all thetrees in the Island of Lewis. Whether these trees in Lewis belong to P. alba,or P. (a.) canescens, may, however, be doubted. Turner, in 1568, says, “thewhite aspe is plentifull in Germany and Italy;” but that he does not rememberto have seen it in England. Gerard, who wrote 30 years after Turner, foundthe white poplar at Blackwall, near London ; at Ovenden, in Essex; and a fewother places. Dr. Walker, writing in 1773, says that it is doubtful whetherthe abele is a native of England; but that it certainly has the appearance ofbeing indigenous in several parts of Scotland. But it must be recollectedthat, in his time, P. alba and P. (a.) canescens were considered as synonymous.He adds, also, that the abele was planted in many places in Scotland about theend of the seventeenth century; and that it had been afterwards neglected anddespised, in consequence of the great number of suckers that it threw up all roundit from its creeping roots. Hartlib, in his Compleat Husbandman (published in1659), states that, some years before the time of his writing, there were 10,000