BUDS ON STEMS. 29 



ment; and these materials are most directly conveyed to them if they are situated 

 as near as possible to the spot where the vascular bundles of a green leaf lead into 

 the stem. 



When a large number of foliage-leaves are packed closely together upon a stem, 

 it is scarcely possible for a bud to be developed in every axil. On such occasions 

 the buds appear always to possess the power of selecting the most convenient points 

 of origin. The majority of leaf -axils are altogether destitute of buds, and it is only 

 at spots where their inception would be most favourable to the plant's development 

 that a few hardy buds are put forth. This is what happens, for example, in most 

 species of Spurge, in the Toad-flax, in Pines and Firs, in Araucarias, and the rest of 

 the numerous family of Conifers. Where buds are formed in the axils of leaves, 

 either there is one to each leaf, or several are crowded together in an axil, and of 

 these one is conspicuous owing to its central position, and also usually for its size, 

 whilst the rest are subordinate. The occurrence on the leafy region of the stem of 

 buds crowded together in this fashion — the meaning of which will be examined in 

 detail in the next few pages — is confined to certain species belonging to the Flora 

 of the Mediterranean, of Australia, and of various Steppe-lands. They are much 

 more commonly found on such regions of the stem as bear scale-leaves, especially in 

 bulbous plants, which sometimes exhibit as many as a dozen little buds springing 

 from the short, thick stem in the axil of one of the expanded scaly leaves of the 

 bulb. 



The buds produced in the floral region of the stem (or inflorescence) usuall}- 

 develop into flowers, and their function being the production of fruit, they cannot 

 be considered until a later section of this work is reached. Meanwhile the bud-form 

 of brood-body is not entirely absent from this region of the stem. Grasses, Saxi- 

 frages, and Polygonums afibrd a great number of examples of their occurrence in 

 that position. 



A wound may cause the formation of a bud at any altitude upon the stem. 

 The bud invariably springs from the injured spot and often no relation can be 

 detected between its point of insertion and the position of the leaves. An instance 

 is known where the herbaceous stem of a Sea-Kale {Crambe maritima) was cut 

 through transversely, and, after the pith had decayed, buds were formed on the 

 inner surface of the vascular-bundle ring from the tissue of the so-called vascular- 

 bundle sheath, and from the buds shoots eventually developed. If the main 

 trunk or a branch of an Angiospermous tree, such as an Oak or Ash, is cut off' 

 smooth, a mass of tissue is formed from the cambium, thus exposed, at the boundary 

 between wood and bast; this tissue gradually creeps out from the margins of the 

 wound and swelling up takes on the form of a circular rampart. The wood- 

 cells which have been cut through and left bare within the circumference of the 

 rampart have not the power of dividing and multiplying so as to initiate a new 

 structure, but are dried up by exposure to the air and perish. The tissue foi'ming 

 the rampart continues, however, to increase in breadth, and encroaches upon the 

 dead interior of the section of the stump so completely that the cut surface of wood 



