Chap. XI. 



GK-VFT-HYBBIDS. 



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, w r hen 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 Cijtisus 

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

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

 and purple laburnum ; but as this tree has often been 

 described, I will be as brief as I can. 



Throughout Europe, indifferent soils and under different climates, 



87 Godron, ' De l'Espece,' torn. ii. p. 

 84. 



88 M. Carriere has lately described, 

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

 1866, p. 457,) an extraordinary case. 

 He twice inserted grafts of the Aria 

 vest it i on thorn-trees < epines) growing 

 in pots ; and the grafts, as the}' grew, 

 produced shoots with bark, buds, 

 leaves, petioles, petals, and flower- 

 stalks, all widely different from those 



of the Aria. The grafted shoots were 

 also much hardier, and flowered 

 earlier, than those on the ungrafted 

 Aria. 



89 ' Transact. Hort. Soc.,' vol ii. p. 

 160. 



90 For the cases of oaks, see Alph. 

 De Candolle in ' Bibl. Univers.,' 

 Geneva, Nov. 1S62; for limes, &c, 

 Loudon's ' Gard Mag.,' vol. xi., 1835, 

 p. 503. 



