Chap. XI. GSAfT-HYBKIDS. 413 



its native woods, the flowers change colour, even during the first 

 year. 87 It is notorious that the improved varieties of the Hearts- 

 ease ( Viola tricolor), when transplanted, often produce flowers widely 

 different in size, form, and colour : for instance, I transplanted a 

 large uniformly-coloured dark purple variety, whilst in full flower, 

 and it then produced much smaller, more elongated flowers, with 

 the lower petals yellow ; these were succeeded by flowers marked 

 with large purple spots, and ultimately, towards the end of the 

 same summer, by the original large dark purple flowers. The 

 slight changes which some fruit-trees undergo from being grafted 

 and regrafted on various stocks, 88 were considered by Andrew 

 Knight 89 as closely allied to "sporting branches," or bud-variations. 

 Again, we have the case of young fruit-trees changing their 

 character as they grow old ; seedling pears, for instance, lose with 

 age their spines and improve in the flavour of their fruit. Weeping 

 birch-trees, when grafted on the common variety, do not acquire a 

 perfect pendulous habit until they grow old : on the other hand, I 

 shall hereafter give the case of some weeping ashes which slowly 

 and gradually assumed an upright habit of growth. All such 

 changes, dependent on age, may be compared with the changes, 

 alluded to in the last chapter, which many trees naturally undergo; 

 as in the case of the Deodar and Cedar of Lebanon, which are 

 unlike in youth, whilst they closely resemble each other in old 

 age; and as with certain oaks, and with some varieties of the lime 

 and hawthorn. 90 



Graft-hybrids. — Before giving a summary on Bud-variation I 

 will discuss some singular and anomalous cases, which are 

 more or less closely related to this same subject. I will 

 begin with the famous case of Adam's laburnum or Cytisus 

 adami, a form or hybrid intermediate between two very dis- 

 tinct species, namely, C. laburnum and purpureus, the common 

 and purple laburnum ; but as this tree has often been 

 described, I will be as brief as I can. 



Throughout Europe, in different soils and under different climates, 



87 Godron, ' De l'Espece,' torn. ii. p. of the Aria. The grafted shoots were 

 84. also much hardier, and flowered 



88 M. Carriere has lately described, earlier, than those on the ungrafted 

 in the 'Revue Horticole,' (Dec. 1, Aria. 



1866, p. 457,) an extraordinary case. 89 'Transact. Hort. Soc.,' vol ii. p. 



He twice inserted grafts of the Aria 160. 



vestita on thorn- trees {epines) growing 90 For the cases of oaks, see Alph. 



in pots ; and the grafts, as they grew, De Candolle in ' Bibl. Univers.,* 



produced shoots with bark, buds, Geneva, Nov. 1862 ; for limes, &c, 



leaves, petioles, petals, and flower- Loudon's ' Gard Mag.,' vol. xi., 1835, 



stalks, all widely different from those p. 503. 



