XV] NUMBERS OF LEAF-TRACES 119 



For instance, there is only one small leaf- trace visible 

 in the small leaf-scars of Daphne, Sea Buckthorn, Sym- 

 phoricarpos, Larch, &c. (Fig. 59 s), and a somewhat larger 

 one of several fused bundles in the Blackthorn, Privet, 

 Almond, and the Spindle Tree (Fig. 59 r). 



Three separate leaf-trace scars are very common in 

 rather small, and crescentic, elliptic, V-shaped, or similarly 

 shaped scars, e.g. in Willows and Poplars, Buckthorn, 

 Genista, Guelder Rose, Wayfaring Tree, Dogwood, Honey- 

 suckles, Elder, Beech, Hornbeam, Pear, Beam, Cherry, 

 Bird Cherry, Laburnum, Apple, Black and Red Currants, 

 Plum, Roses, Blackberry, Elms, and Birch (Fig. 59y, g, h, 

 m, q, u, and v). Even large leaf-scars sometimes have three 

 groups of bundles forming their leaf-traces as in the Fig 

 (Fig. 59 a), but the rule is that large scars have a larger 

 number. 



Four is an exceptional number of leaf-trace scars, 

 but it occurs in the Vine and Virginian Creeper (Fig. 

 59 e). 



Five is a more common number, and occurs in 

 Ailanthus, Rowan, the Sorb, &c. (Fig. 59 c and Z), and is 

 occasionally found in other cases with the bundles more or 

 less approximated or fused into one or more groups, e.g. 

 in Hazel, Hawthorn, Bird Cherry, Lime, White Poplar, 

 Alder, and Mulberry (Fig. 59 o and y). 



The number seven and higher numbers are also fairly 

 common in the Horse-chestnut, Walnut, Oaks, Chestnut, 

 Ash, Rhus typhina, &c., and here again the bundles or 

 traces may be separate (Fig. 59 6) or more or less grouped 

 (Fig. 59 i y k, n) or fused in various ways (Fig. 59 d, p, x). 

 It is not always possible to insist on these numbers 

 exactly, because weaker or smaller leaves on one and the 

 same twig may occasionally have fewer traces than those 

 found in the leaf- scars of normal leaves, but the approximate 



