io6 FLOWERS OF THE WOODS AND COPSES 



One seldom finds any Poplars in a really native state in any situation 

 except in woods, for owing' to their quick growth they are much 

 planted in hedgerows and plantations. But the Aspen, which grows 

 in damp, moist woods or by water, may well be native in such stations, 

 and it is seldom found in any other habitat, as are the others which are 

 also found in woods. 



The Aspen is an erect, rather distantly branched tree, with a rather 

 short stem and slender branches. The bark is grey. The suckers are 

 downy, as also are the buds, which are not clammy. The leaves are 

 sub-entire, nearly round, broadly toothed, smooth both sides. The 

 leaf-stalks are flattened. Those at the top are on long stalks, and are 

 rounded with wavy margin. The radical shoots have short stalks and 

 nearly triangular leaves. 



The blade of the leaf is inserted on the vertically flattened leaf- 

 stalk, hence their tremulous character. Rain falls and runs down the 

 petioles or stalks, where 2 cups catch and hold it, the cells being thin- 

 walled secrete a resin, swelling when moistened, and the cells absorb 

 the moisture, being protected in dry weather by the resinous deposit. 



The catkins are cylindrical, with hairy male catkin scales with 

 narrow lobes. The 2 stigmas are divided into two nearly halfway, 

 seared. 



The tree is 40-80 ft. high. It is in flower in March till April. 

 The plant is a deciduous tree, propagated by seeds. 



Unlike the Willow, with the floral mechanism of which it agrees in 

 most respects, the Aspen is pollinated by the wind, and has no honey. 

 The stamens are more numerous than in Sa/i.v, 4-30, the anther-stalks 

 free, the stigmas are slender and 2-4-fid. 



The seeds are clothed in cottony appendages to aid in their dis- 

 persal by the wind. 



The Aspen is a humus-loving plant, growing in a humus or peaty 

 soil. 



Several fungi attack the Aspen, especially Mclampsora trcnnthe, 

 and the petioles are galled by Diplosis trcmnhr. It is attacked also 

 by Exoascus, Tympanis, Lentinus, Hypholoma, Pholiota, Plcurotus, 

 Collybia, Fomes, Polyponis. 



It is galled by Saperda populnea arid Eriophycs pustulahiw. 

 Numerous other insects attack it, such as Saperda carcharias, Mela- 

 soma populi, Cladiusviminalis (Poplar Hawk Moth), Smerinthus populi* 

 Dicranura vinula (Puss Moth), Pemphigus bursarius, P. spirothecfc, 

 Ortho-stylus bilincatus, Phytocoris populi, Pediopsis nassatus, Idiocerus 

 trcmulte, I. fitlgidus, I. populi, &c. 



