LEAF-BUDS AND BKANCHES. 



109 



ka. 



Fig. 219. 



formed continuous with those of the stem ; and, ultimately, branches 

 are produced, which in every respect resemble the axis whence the 

 buds first sprang. The cellular portion in the 

 centre remains as pith with its medullary sheath, 

 which is closed and hot continuous with that 

 of the parent stem. Thus, in the stem and 

 ■ branch, this sheath forms a canal which , is 

 closed at both extremities, and which sends 

 prolongations of spiral vessels to the leaves. 

 As the axis or central portion of the leaf-bud 

 increases, cellular projections appear at regular 

 intervals, which are the rudimentary leaves. 



A leaf-bud may be removed in a young 

 state from one plant and grafted upon another, 

 by the process of hudding, so as to continue to 

 form its different parts ; and it may even be 

 made to grow in the soil, in some instances, 

 immediately after removal. In certain cases 

 leaf-buds are naturally detached during the life of the parent, so as to 

 form independent plants, and thus propagate the individual. Leaf- 

 buds have on this account been called fixed embryos, by Petit-Thouars 

 and others, who' look upon them as embryo plants fixed to the axis, 

 capable of sending stems and leaves in an upward direction, and bast 

 or ligneous fibres downwards, which, according to them, may be con- 

 sidered as roots. A tree may thus be said to consist of a series of 

 leaf-buds, or phytons {furh, a plant), attached . to a common axis or 

 trunk. In ordinary trees, in which there is provision made for the 

 formation of numerous lateral leaf-buds, any injury done to a few 

 branches is easily repaired ; but in Palms, which only form central 

 leaf-buds, and have no provision for a lateral formation of them, an 

 injury iaflicted on the bud in the axis is more likely to have a 

 prejudicial effect on the future life of the plant. 



In the trees of temperate and cold climates the buds which 

 are developed during one season lie dormant during the wiater, ready 

 to burst out under the genial warmth of spring. They are generally 

 protected ^by external modified leaves in the form of scales, tegmenta 

 or perulm (tegmenta, coverings ; peridx, small bags), which frequently 

 exhibit a firmer and coarser texture than the leaves themselves. 

 These scales or protective appendages of the bud consist either of the 

 altered laminae, or of the enlarged petiolaiy sheath, or of stipules, as 

 in the Fig and Magnolia, or of one or two of these parts combined. 



"Fig. 219. Upper portion of a branch of Lonieera nigra in a state of hibernation, that is 

 to say, after the fall of the leaves ; covered with leaf-huds. it, A. terminal bud. 6a, 6a, 

 6(8, Axillary lateral buds. Below the buds the cicatrix or scar left by the fallen leaves 



