WINTER-BUDS. 



43 



buds are formed, which are situated at the end or at the sides of the branch as special 

 organs. When a winter-bud is about to be formed at the end of a leaf-shoot, 

 e. g. of a Fir, Oak, Horse-chestnut, &c., the development of foliage-leaves suddenly 

 ceases, and a number of corresponding leaf-rudiments assume the form of scales, 

 which tightly surround the younger parts, and are often glued together with resin or 

 balsam. Very commonly, it is the lateral shoots of woody plants which on their origin 

 assume at once the form of winter-buds, and commence with the formation of scale- 

 leaves. In some special cases, as in the Fir and Pine, the apex of the shoot which 

 becomes developed in the next period of vegetation into the leaf-shoot, is already 

 present in a quite embryonic state, enveloped by the bud-scales. In other cases, 

 again, as in the Horse-chestnut and our fruit trees, we find already in the autumn, 

 within the winter-bud, not only the end of the young shoot, but a branch-system, 

 with flower buds and more or less developed foliage leaves, and all these parts 

 already so far formed, that the first warm days of spring sufiice to bring them to 

 complete development, after the bud-scales 

 have opened. 



In herbaceous plants it often occurs 

 that all the organs produced in one 

 period of vegetation — ^root, shoots, and 

 flowers — completely disappear, and that only 

 a few buds, with or without enveloping 

 scales, remain over the winter ; and, de- 

 veloping in the next spring and forming 

 new roots, represent a new transitory 

 plant individual. So it is in many water 

 plants, as Aldrovanda vesiculosa and Uivi- 

 cularia, and many land plants, where 

 the bud, remaining behind in connection 

 with a reservoir of reserve material, repre- 

 sents a tuber, capable of germinating, as in 

 our species of Ophrys, in the Arrow-head 

 (Sagittaria), Crocus vernus, and in Ficaria 

 ranunculoides, &c. Strictly speaking, bulbs 

 also are only peculiarly developed persistent 

 buds, the outer leaves of which are thick, 

 swollen, and filled with reserve materials, the substances which are used in the 

 beginning of the period of vegetation for the development of the young shoot- 

 rudiments in the interior of the bulb. One need only cut through a common 

 kitchen onion {Allium Cepd), in the direction of its length, or a Hyacinth or Tulip 

 bulb, in autumn or winter, in order to recognise the state of affairs at once. 



Entering now more closely upon the study of the organisation of the shoot, 

 it is better to consider the shoot-axis and leaves separately. No one will ^wish 

 to compare the organisation of. the leaves with that of the root; but the typical 

 form of the shoot-axis, with its cylindrical or prismatic figure, suggests a comparison 

 between it and the root. In spite of this external similarity, however, the organisation 

 of the leaf shoot-axes is vtry strikingly different from that of the roots. If the fully 



Fig. ,^5 — Longitudinal section through the apical region o 

 a bud ol Equtseiitm ar-vense, ss apical cell ; b — bx the sheath - 

 like leaves (magnilied). 



