Populus 1787 



POPULUS TREMULA, Aspen 



Populus tremula, Linnaeus, Sp. PL 1043 (1753); Loudon, Arb. et Frut. Brit. iii. 1645 (1838); 

 Wesmael, in Mim. Soc. Sc. Hainaut, iii. 229 (1869), and De Candolle, Prod. xvi. 2, p. 325 

 (1864); Willkomm, Forstl. Flora, 521 (1887); Mathieu, Flore Forestiire, 486 (1897); 

 Schneider, Laubholzkunde, i. 19 (1904); Dode, in Mim. Soc. Hist. Nat. Autun, xviii. 30 

 (1905); Ascherson and Graebner, Syn. Mitteleurop. Flora, iv. 24 (1908) ; Gombocz, in Math. 

 Termes. Kdzl. xxx. 123 (1911). 



Populus australis, Tenore, Ind. Sem. Hort. Neap. 1830, p. 15. 



Populus graca, Grisebach, Spic. Fl. Rum. ii. 345 (1844) (not Aiton, Hort Kew.). 



A tree, occasionally attaining in Scandinavia, Russia, France, and Germany 100 

 ft. in height and 6 to 8 ft. in girth, but usually much smaller, especially in the British 

 Isles. Bark of young trees smooth, thin, greenish or whitish ; on old trunks 

 thick, with small rhomboidal fissures, as in P. alba, and ultimately deeply furrowed. 

 Young branchlets glabrous, rounded, shining, with orange lenticels. Buds ovoid, 

 acute, shining brown, slightly viscid, with ciliate scales, the uppermost of which 

 are slightly pubescent. Leaves (Plate 408, Fig. 4) suborbicular, variable in size, 

 averaging 2 in. in diameter, thin in texture, truncate or subcordate at the base, 

 rounded or acute at the apex ; margin with a narrow translucent border, and a few 

 rounded or sinuate small teeth ; tomentose when young, speedily becoming glabrous 

 on both surfaces, pale or glaucous beneath ; venation pseudo-five-palmate ; glands ^ at 

 the base two, cup-shaped, well -developed on the terminal leaves of long vigorous 

 shoots, absent on the basal leaves and on those of the short shoots ; petioles 

 slender, glabrous, laterally compressed, often as long as the blade. Leaves on young 

 plants and on sucker shoots, and in rare cases on sporadic branches of adult trees, 

 different in shape and much larger, 4 to 5 in. long, 3 to 4 in. broad ; ovate, acumi- 

 nate at the apex, truncate or cordate at the base, greyish and slightly woolly beneath, 

 glandular-serrate, with short pubescent terete petioles. 



Catkins sub-sessile, densely and greyish tomentose ; axis pubescent ; scales long 

 persistent, obovate, deeply lobed and fringed with long white hairs ; flowers dense, 

 numerous, on very short pilose pedicels. Stamens about 10, with short filaments 

 and purple anthers, on an oblique disc with an entire and incurved margin. Ovary 

 glabrous ; stigmas two, reddish, each divided, forming four widely dilated curving 

 arms ; disc funnel-shaped, oblique, glabrous ; capsule two-valved. 



This species in the wild state displays a considerable amount of variation in the 

 shape, size, and colour of the leaf, and in the amount of pubescence on the branchlets 

 and leaves. The most noteworthy ^ are : — 



I. Var. Freyni, Hervier,. in Bull. Herb. Boiss. iv. app. i. 18 (1896), and Rev. 

 Gen. Bot. viii. 177 (1896). Leaves rhombic, cuneate at the base, ciliate, pubescent 

 beneath when young. Central France and Prussia, 



1 According to Kerner, Nat. Hist. Plants, Eng. Trans, i. 238, fig. 55 (1898), these glands exude resin and serve for 

 absorbing water in rainy weather; but Trelease, in Bot. Gaz. vi. 284 (1881), states that they contain honey at the beginning 

 of the season, and are visited by bees and other insects. 



2 Var. purpurea, Simon-Louis, ex Spath, Cat. No. 102, p. 108 (1898-1899), with purplish young leaves, does not seem 

 to differ from the type, as seen in cultivation at Kew. 



