642. The Trees of Great Britain and Ireland 



angle, generally directed forwards, about i^ inch long; wings green, narrow below, 

 scimitar-shaped. Seed obovate, without albumen ; cotyledons narrow, long, either 

 spirally coiled or plicate. 



Seedling} Cotyledons normally two, rarely three, carried above ground on 

 germination, i^ to 2 inches long, oblong, sessile, obtuse, entire in margin, 

 obscurely three-nerved, glabrous, pale-green. Caulicle, \ to i inch long, glabrous, 

 ending in a tapering, flexuose, primary root, which gives off a few lateral fibres. 

 Young stem terete, glabrous. First pair of leaves, ovate, cordate at the base, 

 palmately five-nerved, acuminate, irregularly serrate. Second and third pairs 

 similarly cordate and five - nerved, distinctly three - lobed ; terminal lobe long, 

 triangular-ovate ; lateral lobes short, broad, with two indistinct lobules or teeth. 

 Succeeding pairs resemble those of the adult plant. 



Seedlings with three cotyledons, observed by Sir W. Thiselton Dyer," bore 

 leaves in whorls of threes in their first and second years ; but in the third and 

 following years they reverted to the ordinary type with opposite leaves. 



Identification 



In summer the sycamore is readily distinguishable by the shape of the leaves, 

 and can only be confused with A. insigne, from which it differs markedly in the 

 buds, as explained under the latter species. 



In winter the twigs are shining, glabrous. Buds sessile, ovoid ; terminal 

 buds larger than the lateral buds, which arise from the twigs at an angle of 45'; 

 scales, six to eight visible externally, in opposite decussate pairs, green with dark 

 edges, glabrous or slightly pubescent near the tip, ciliate in margin. Leaf-scars 

 not joining around the twig, crescentic or V-shaped, three-dotted. The bud-scales 

 are homologous with leaf-bases, and fall off when the bud opens, showing at this 

 stage a minute three-lobed projection at the tip, which corresponds to a leaf- 

 blade. 



Varieties 



The sycamore is remarkably constant in foliage in the wild state,^ only one 

 well-marked geographical form being known : 



Var. villosa, Parlatore, Fl. Ital. v. 404 (1872). Leaves coriaceous ; base widely 

 cordate, margin coarsely toothed, lower surface pubescent throughout in early 

 spring. Fruits usually tomentose, with very broad wings. This variety occurs in 

 the mountains of Sicily, Calabria, and Dalmatia. 



In the common wild form the leaves are scarcely coriaceous, and are only 

 pubescent along the nerves beneath, while the fruit is glabrous. From the common 

 form, numerous varieties have arisen in cultivation, as many as fifty being 



' Cf. Lubbock, Seedlings, i. 360, f. 252 (1892). 



' Antt. of Botany, xvi. 553, plate xxiv. (1902). In plate xxv. an abnormal seedling is figured, in which three cotyledons 

 are followed by two leaves, one of which is bi-partite. Cf. Loudon, of. at. p. 4lS' 



* On a tree growing in TuUymore Park, Co. Down, Ireland, many of the branchlets bore the leaves alternately and not 

 in pairs. Specimens of this were sent to the Kew Herbarium in 1871. 



