30 FUNCTIONS OF PLANTS. 



from maturing its buds and wood, and consequently deprived of the power of 

 growing vigorously the following season ; and this is found a better mode 

 of treating excessively luxuriant trees than cutting off such over- vigorous 

 shoots, which would only throw more vigour into the heart of the tree. 

 By taking off the incipient leaves the tree is allowed to exhaust itself of all 

 its superfluous force. See Beaton in Gard. Mag. 1837, p. 203. 



114. In general, buds are rarely found except in the axils of the leaves; but 

 occasionally they are formed in the spaces of the stem between the leaves, more 

 or less distant from the base of the leaf, or from the joints whence leaves are pro- 

 duced. They are also, as we have before observed, sometimes found in roots, 

 though never visible in them to the naked eye ; and they are also produced 

 in some cases on leaves, as in Kalanchbe (Bryophyllum) crenata, and in Car- 

 damine hirsuta. Buds of this kind are said to be dormant or adventitious. 

 When the bud of any stem has been once matured, if rubbed off, one or 

 more other buds will arise from its base ; and this will take place though 

 the operation be repeated an indefinite number of times, provided the plant 

 be furnished with leaves in some other part of its stem above the point 

 whence the buds were rubbed off, so that the shoot or stem may be continued 

 in a growing state. Thus the regular visible buds of vines are frequently 

 cut entirely out, but still the adventitious buds throw out shoots with such 

 vigour, other circumstances being favourable, as to produce abundance of 

 fruit the same season. 



115. Buds are of two kinds, leaf-buds and blossom-buds. It is only the 

 former that can produce shoots, or by which, under ordinary circumstances, 

 a plant can be propagated directly. But if a blossom-bud be taken off and 

 inserted in a living plant by the usual operation of budding, though only 

 blossoms will be produced the first year, yet the dormant leaf-buds will the 

 second year produce shoots. In practice this does not hold good alike in all 

 plants, but it is the case with many of the Rosaceae, for example in the 

 Peach. The nodule is a concretion of embryo buds found in the bark .of 

 various trees, and especially of the common Elm, the Birch, some of the 

 Poplars, and the Olive; and by fragments of which these trees may be 

 propagated. 



110. All bulbs are buds, and the scales of which they are composed are 

 abortive or imperfectly developed leaves ; consequently, as at the base of 

 every leaf there is a bud, so must there be, at the base of every scale of 

 a bulb, a bud either regular or adventitious. Hence, by cutting over the 

 bulb of a common Hyacinth about the eighth of an inch above the plate to 

 which the scales are attached, a number of buds and young leaves will be 

 produced from between the bases of the scales, and by these buds the plant 

 may be increased. 



117. The stem of a plant may be considered as the base, receptacle, or 

 habitation of the leaves and buds ; by means of which they are exposed to the 

 air and light, without being too much crowded, and are thus enabled to elabo- 

 rate the sap sent to them by the roots, and to form buds and seeds for the 

 continuation of their species. The watery matter absorbed by the spongioles 

 ascends the stem by the soft wood, dissolving in its ascent a part of the starch 

 or sugar which it finds there, and hence becoming denser as it ascends ; its 

 specific gravity increasing till it reaches the summit of the stem and branches. 

 As it ascends it enters the leaves, where it is elaborated in consequence of the 

 action of light on their upper surface, and it is then returned to the stem by 



