252 The Trees of Great Britain and Ireland 



separating from one another. The pollen then falls into a depression on the side 

 of the neighbouring flower below, from which it is shaken out by the wind and 

 carried to neighbouring branches of the tree, where it alights on the stigmas of 

 the female flowers. 



Seedling ' 



The cotyledons are large, fleshy, obovate, bi-lobed and crumpled, filling the 

 cavity of the seed, from which they do not emerge on germination, but remain 

 underground. The primary root makes its exit by the apex of the nut, and 

 becomes stout and flexuose, giving off a few lateral fibres. The cauHcle is very 

 short, stout, and woody. Young stem, erect, compressed, glabrous, greenish, and 

 covered with lenticels. The first four pairs of leaves are mere scales, opposite 

 or sub-opposite on the stem. The ninth leaf is foliaceous, and consists of three 

 leaflets, the terminal one large, obovate or elliptical, and cuspidate, the lateral ones 

 small, oblong and alternate. The next leaf is five-foliolate ; the terminal leaflet, 

 oblong-obovate ; the middle pair ovate, acuminate, oblique at the base, unequal, and 

 sub-opposite ; the basal pair small, ovate, oblique, and unequal. The last leaf is 

 like it, or bears only four leaflets. All these primary leaflets are serrate in margin, 

 and more acuminate than those of the adult plant, which are entire. In these respects 

 they resemble the adult leaves of Carya or other species of Juglans.* 



Identification 



The common walnut is distinguishable in summer from all the other species by 

 its glabrous, entire, few leaflets. In winter the following characters are available : 

 Twigs stout, glabrous,' shining, greenish or grey, with scattered longitudinal lenticels. 

 Leaf-scars on prominent pulvini, broadly obcordate, the upper margin deeply notched 

 in the centre and not surmounted by a band of pubescence ; bundle-dots in three groups. 

 Pith large, white or buff in colour, with wide chambers. Terminal bud ovoid, obtuse 

 at the apex, with four external grey tomentose scales in two valvate pairs, the scales 

 not lobed at their apex and merely representing leaf-bases. In many cases, as in 

 slow-growing old trees, the true terminal bud is aborted on most of the branchlets, and 

 its scar marks the end of the twigs. Lateral buds small, arising at an angle of 45, 

 globose, the two outer scales usually concealing the inner ones, pubescent at first, but 

 ultimately becoming glabrous. Superposed lateral buds occur only rarely. 



Varieties 



Two distinct geographical forms are known : 



(a) typica, in Europe, Asia Minor, Persia, and the Himalayas. Leaves elliptic ; 

 nuts ovoid-globose with thin septa. 



{b) sinensis, C. DC. in Ann. Sc. Nat. 4 S^r. xviii. 33, figs. 38, 39. North 



> Cf. Lubbock, Seedlings, ii. 516, fig. 661 (1902). 2 Cf. Fliche, Bull. Soc. des Sciences, Nancy (1886). 



' Some varieties of cultivated walnuts have the twigs covered with a minute pubescence. 



