174 SCALES OF BUDS ARE LEAVES. [BOOK i. 



smooth, and dry ; in many Willows they are covered with a 

 thick down ; in Populus balsamifera they exude a tenacious 

 viscid juice. In herbaceous plants and trees of climates in 

 which vegetation is not exposed to severe cold, the leaf-buds 

 have no dead scales; which is also, but very rarely, the 

 case in some northern shrubs, as Khamnus Erangula. / 



The scales of the bud, however dissimilar in their ordinary 

 appearance they may be to leaves, are nevertheless, in reality, 

 leaves in an imperfectly formed state. They are the last 

 leaves of the season, developed at a period when the current 

 of vegetation is stopping, and when the vital powers have 

 become almost torpid. That such is their nature is suffi- 

 ciently shown by that gradual transition from scales to perfect 

 leaves which occurs in such plants as Viburnum prunifolium, 

 Magnolia acuminata, Liriodendron Tulipifera, and ^Esculus 

 Pavia : in the latter the transition is, perhaps, most satisfac- 

 torily manifested. In this plant the scales on the outside are 

 short, hard, dry, and brown ; those next them are longer, 

 greenish, and delicate ; within these others become dilated, 

 are slightly coloured pink, and occasionally bear a few imper- 

 fect leaflets at their apex ; in succession are developed leaves 

 of the ordinary character, except that their petiole is dilated 

 and membranous like the inner scales of the bud ; and, finally, 

 leaves perfect in all their parts complete the series of tran- 

 sitions. 



Among the varieties of root is sometimes classed what 

 botanists call a bulb ; a scaly body, formed at or beneath the 

 surface of the ground, emitting roots from its base, and pro- 

 ducing a stem from its centre. Linnaeus considered it the 

 leaf-bud of a root ; but in this he was partly mistaken, roots 

 being essentially characterised by the absence of buds. He 

 was, however, perfectly correct in identifying it with a leaf- 

 bud, from which it differs in nothing more than in being 

 deciduous, and consisting of scales much more fleshy than in 

 ordinary leaf-buds. In some plants, such as the Tiger Lily, 

 the leaf-buds, in their usual position, in the axils of leaves, 

 acquire a fleshy consistence, and are spontaneously cast off 

 by the stem in the state of true bulbs. 



A bulb has the power of propagating itself by developing 



