POPULUS 



Populus, Linnaeus, Gen. PL 307 (1737) and 456 (1754), Sp. PL 1034(1753); Wesmael, in De 

 Candolle, Prod. xvi. 2, p. 323 (1868), in M6m. Soc. Set. Hainaut, iii. 186-250 (1869), and in 

 BulL Soc. Bot. Belg. xxvi. pt. i. p. 371 (1887); Bentham et Hooker, Gen. PL iii. 412 (1880); 

 Schneider, Laubholzhunde, i. 2-23 (1904), and ii. 869, 870 (1912); Dode, in Mim. Soc. Hist. 

 Nat. Autun. xviii. 1-76 (1905); Ascherson and Graebner, Syn. Mitteleurop. Flora, iv. 14-54 

 (1908); Gombocz, in Math. Termes. KozL xxx. 5-238, with two maps (1911). 



Deciduous trees, belonging to the natural order Salicaceae. Terminal buds large, 

 with one or two outer pairs of opposite scales at the base, and several imbricated scales 

 above ; axillary buds smaller, with fewer scales, the lowest of which is short, broad, 

 and open next the stem ; scales accrescent, marking when they fall the base of the 

 branchlet with ring-like scars. Branchlets terete or angled, with five-angled pith, 

 and showing, when the leaves have fallen, three-dotted leaf-scars, on the sides of which 

 are visible two minute scars left by the early deciduous stipules. Leaves simple, 

 alternate, penninerved, usually long-stalked ; entire, dentate, or lobed ; often different 

 in shape, pubescence, and margin on the long and on the short shoots. 



Flowers without honey, fertilised by the wind, appearing before the leaves in 

 early spring ; dioecious, in pendulous stalked catkins, which arise from buds in the 

 axils of the leaf-scars of the previous year or at the ends of short shoots. Catkins 

 bearing on a slender axis numerous flowers, each of which is subtended by a 

 caducous stalked lobed, dentate, or laciniate scale (bract). Perianth absent, replaced 

 by a stalked disc. Male flowers densely crowded ; stamens four to twelve, or 

 twenty to sixty, with short white filaments, and purple or red two-celled anthers, 

 arising from the oblique, flat or concave disc. Pistillate flowers not so dense in the 

 catkin as the male flowers ; ovary sessile in the oblique cup-shaped disc, one- 

 celled, with two, three, or four placentse ; style short or obsolete, with as many 

 entire or bifid stigmas as there are placentae. Fruiting catkins elongated, ripening 

 early before the leaves are fully grown ; capsule one-celled, separating when ripe 

 into two to four recurved valves, girt at the base by the persistent disc.'^ Seeds 

 numerous, minute, without albumen, elliptic, compressed, acuminate at the apex, 

 surrounded by tufts of long white silky hairs, attached to their short stalks and 

 deciduous with them. Seedling,^ with two stalked suborbicular cotyledons, sagittate 

 at the base, thick and succulent; primary leaves either in opposite pairs as in 

 P. canescens, or alternate as in the black poplars. 



1 In section Turanga the disc is deciduous, and does not persist on the fruit. 



2 An account of the germination of poplars, with figures of the seedlings, is given by Miss F. H. Woolward, in Journ. 

 Bot. xlv. 417, t. 487 (1907). Cf. also Hickel, in Bull. Soc. Dmd. France, No. 25, p. 88 (1912). 



1770 



