[A55]

Gard. Chronicle 1871. p. 1420 - 2 forms of nervation on same Beech-leaf.

Means of Transition - Alph. De Candolle.

 

[Some few years since, M. Alph. de Candolle drew attention to the arrangement of the Veins of the Leaf in some species of Beech (Fagus), in which he pointed out that the lateral veins, instead of running up into the centre of the little lobes or teeth of the margin of the leaf, as is usually the case, terminated in the sinus or notch between them. Although in some cases

both forms of nervation exist in the same leaf (a caution to fossil botanists), yet in other cases it appeared to M. De Candolle to be sufficiently constant to be used as a specific character. In this manner, for instance, M. DE Candolle distinguishes our European Beech, in which the tendency is for the veins to run into the shallow notches of the leaf, from the American form, where the veins run into the teeth or lobes.

M. De Candolle also cites as illustration of this unusual direction of the nerves, Coldenia procumbens, Cratægus Oxyacantha, the Hawthorn, and Rhinanthus. To this list, no doubt, many additions could be made; one is before us as we write, in the leaves of Ceratopetalum gummiferum. We have also seen a similar arrangement in the linear leaves of some Dryandra or allied Proteaceous plant; in some Saxifrages, e.g., S. Geum, in Betonica officinalis, and obscurely in Hieracium murorum, Teucrium Chamædrys, and Tussilago fragrans. The point is one of some importance in structural botany, not only with reference to fossil leaves and their appropriate discrimination, but also to such cases as the venation of the flowers of Composites, and of the so-called gamopetalous corollas in general.

- 1871. Gardeners' Chronicle, part 2 (4 November): 1420.]