Ill] BUD-SCALES 27 



We have seen that the bud-coverings are essentially 

 leaf-structures. Sometimes these bud-coverings are merely 

 unaltered leaves, just like any other leaves of the plant, 

 and this is probably always the case when the bud is 

 merely the end of the still growing shoot, as in most 

 herbaceous plants ; but even in buds which are adapted 

 for resting through the winter this is sometimes so. Such 

 naked buds occur in Viburnum nudum, V. Lantana, 

 Rhamnus Frangula, Juniper, and many herbs. 



As a rule, however, the winter buds of our colder 

 climates are covered with bud-scales of quite different 

 texture from the foliage leaves : these scales are thrown 

 off in the spring when the buds expand. The bud-scales 

 may be simply dry, papery or leathery in texture, and 

 brown (Beech, Prunus Avium), or greenish (Lilac, Acer 

 pseudoplatanus) ; or more or less hairy (Juglans, Betula 

 pubescens, Carpinus, Ulmus, &c.) f velvety (Ash), glandular 

 (Hippophae, Elceagnus, Betula, verrucosa), or viscid, owing 

 to resinous or gummy excretions (Alnus glutinosa, Populus 

 canadensis and P. nigra, and Horse-chestnut). In all these 

 cases the texture, hairy covering, and resinous or balsamic 

 excretions are protective, in that they prevent rapid 

 changes of temperature and especially loss of moisture, 

 and this protection is sometimes supplemented by cottony 

 hairs covering the young organs inside the scaly covering, 

 e.g. the Horse-chestnut. 



The bud-scales (apart from those cases where they are 

 obviously ordinary leaves) may be seen to be more or less 

 modified leaves by tracing them from without inwards as 

 the bud opens in spring. In the Lilac, Lonicera and 

 Daphne the scales pass gradually into ordinary leaves 

 and are modified forms of their blades : in Magnolia, 

 Liriodendron, Alder, Beech, Oak, Ficus elastica and many 

 others the bud-scales are stipules, the leaves to which 



