72 



MOEPHOLOGT, OB COMPAEATITE ANATOMY. 



When winter-buds swell and open, throwing- off their scales, the inter- 

 nodes between the latter do not elongate, while those between the nas- 

 cent leaves do ; consequently the starting-point of each annual period 

 of growth of a branch with an indefinitely developed terminal bud is 

 indicated by a little band of scars marking the place where the scales 

 stood. 



Fig. 123. 



Fig. 124. 



Fig. 123. Section of the end of a shoot of the Horae-chestnut, showing the terminal and two 

 axillary buds ; the terminal bud contains an inflorescence, surrounded by scales 

 and rudimentary leaves. 



Fig. 124. Bud-scales a, 6, and rudimentary leaves c, d, from the winter-bud ofPrunus Avium. 



The first two scales of a bud of a dicotyledonous plant, like the 

 two cotyledons of the embryo, usually stand right and left of the 

 axil on which the bud arises ; the succeeding scales assume at once 

 the regular character of arrangement of the leaves of the species. 



In winter-buds there is commonly a gradual transition from the pure 

 scale to the true leaf (fig. 124), as occurs in bulbs ; and the scales, as in 

 bulbs, are referable chiefly to the vaginal or petiolar portion of the leaf. 

 Bat the scales originate differently in different cases : thus we have 

 petiolar scales, as in the Walnut and Horse-chestnut ; stipidar scales, as in 

 the Vine, Oaks, Elm, Poplars, &c. ; in this case, however, especially in 

 the outer scales, the stipules and the petiole are confluent into one organ 

 (Pmmts, Rosa, &c.) (fig-. 124). Foliaceous scales are formed by the blade 

 of the leaf, of which we have examples in the Lilac, Maples, Conifer, 

 &c. 



Vernation. The mode in which rudimentary leaves are arranged 

 in leaf-buds is called the vernation, and furnishes important syste- 

 matic characters. Two points have to be regarded here, viz. : 

 1, the arrangement of the leaves in relation to each other ; and, 



