1772. The Trees of Great Britain and Ireland 



II. Leuce, Duby, in De Candolle, Syn. PI. Fl. Gall. i. 427 (1828). 



White poplars and aspens. - Bark smooth on young stems, ultimately 

 breaking on the surface into rough rhombic cavities. Buds variable, tomentose 

 and dry, or glabrous and viscid. Leaves variable, tomentose or glabrous; 

 lobed, dentate, or serrate. Flower scales fringed with long hairs ; stamens few, 

 about ten ; capsules slender, oblong. 



A. White poplars.— Leaves densely tomentose on the long shoots ; less tomentose 



or glabrescent, and different in shape on the short shoots. 



2. Populus alba, Linnsus. Europe, North Africa, Asia Minor, Caucasus, Central 



Asia, Himalayas. Seep. 1777. 

 Leaves on the long shoots palmately lobed, snowy white beneath ; on the 

 short shoots oval, dentate, greyish beneath. 



3. Populus tomentosa, CaxnhrG. North China. See p. 1786. 



Leaves on the long shoots triangular-ovate, without lobes, biserrate, grey 

 tomentose beneath ; on the short shoots, with a few sinuate teeth, glabrescent 

 beneath. 



4. Populus canescens. Smith. Western Europe. See p. 1780. 



Leaves on the long shoots ovate -deltoid, greyish white beneath, with 

 irregular triangular serrated teeth ; on the short shoots suborbicular or broadly 

 ovate, glabrescent beneath, with a few sinuate teeth. 



B. Aspens. — Leaves on the long and short shoots not markedly different, glabrous 



or glabrescent beneath. 



* Branchlets glabrous. 



5. Populus tremula, Linnaeus. Europe, North Africa, Asia Minor, Caucasus, 



Siberia. See p. 1787. 

 Leaves suborbicular, i^ to 2 in. in diameter, thin in texture, acute or 

 rounded at the apex ; margin with rounded or sinuate teeth. 



6. Populus tremuloides, Michaux. North America. See p. 1791. 



Leaves orbicular or ovate, i^ to 2 in. in diameter, thin in texture, cuspidate 

 at the apex ; margin ciliate, finely and regularly serrate. 

 * * Branchlets slightly tomentose. 



7. Populus Sieboldii, Miquel. Japan. See p. 1794. 



Leaves ovate, 3 in. long, 2 in. wide, thick in texture, shortly acuminate at 

 the apex ; margin with minute sinuate teeth or glandular serrations. 



8. Populus grandidentata, Michaux, North America. See p. 1792. 



Leaves ovate-deltoid, 3 to 4 in. long, 2 to 3 in. wide, thin in texture, 

 acuminate ; margin with a few sinuate triangular large teeth. 



III. AiGEiROs, Duby, in De Candolle, Syn. PI. Fl. Gall i. 427 (1828). 



Black poplars. — Trees with furrowed bark. Buds viscid, but not very 

 odorous. Leaves green on both surfaces, with a clearly defined translucent 

 border. 



