MORPHOLOGY 



23 



where the rainfall is evenly distributed throughout the year buds 

 develop no such means of protection. 



In many deciduous trees, such as the Willow, the terminal buds of the year's 

 growth regularly die. In nearly all trees many buds, iisually the first-formed 

 buds of each year's shoot, seem able to remain dormant during many years without 

 losing their vitality : these are termed DORMANT BUDS. In the case of the Oak or 

 Beech such latent buds can endure for hundreds of years ; in the meantime, by 

 the elongation of their connection with the stem, they continue on its surface. 

 Often it is these, rather than adventitious buds, which give rise to the new growths 

 formed on older parts of stems. It may sometimes happen that the latent buds 

 lose their connection with the woody parts of their parent stem, but nevertheless 

 grow in thickness, and develop their own wood ; they then form remarkable 

 spherical growths within the bark, which may attain the size of a hen's egg and 

 can be easily separated from the surrounding bark. Such globular shoots are 

 frequently found in Beech and Olive trees. 



i, 



FIG. 23. Rhizome of Polygonatum tnultiflorum. a, Bud of 

 next year's aerial shoot ; b, scar of this year's, and 

 c, d, e, scars of three preceding years' aerial shoots ; , 

 roots. (^ nat. size.) 



FHJ. 22. Shoot of Dentaria bulbi 

 fera, bearing bulbils, br. , (Nat. 

 size.) 



The Metamorphosis of the Bud. The BULBILS and GEMLE> 

 which become separated from the parent plant and serve as a means 

 of reproduction, are special forms of modified buds. To facilitate 

 the storage of reserve nutritive substances they have usually the form 

 of small tuberous bodies. Many plants owe their specific name to 

 the fact that they produce such bulbils, as, for example, Lilium 

 bulbiferum and Dentaria bulbifera (Fig. 22). 



The Metamorphosis of Subterranean Shoots. Shoots that live 

 underground undergo characteristic modifications, and are then termed 



