Observations on the Purple Laburnum. 289 



Art. II. On the singular Origin of the Purple Laburnum, and on 

 the nexxi Field uohich it opens to the Horticulturist for the Production 

 of Hybrid Plants. By the Hon. and Rev. W. Herbert, D.C.L. 

 F.H.S. &c. 



I AM much obliged to you for the opportunity you have given 

 me of reading M. Poiteau's interesting account of tlie origin of 

 the purple laburnum, or Cytisus Adam/, which I had under- 

 stood to be an accidental hybrid produced in the garden of M. 

 Adam, but which is stated, and (I doubt not) correctly, to have 

 originated from a graft of C. purpiireus, of which the bud had 

 perished. I am not aware what the hypothesis of M. Prevost 

 and M. Leclerc, to which M. Poiteau alludes, may be ; but I 

 think I understand how this singular plant must have been pro- 

 duced, and, if I am right in my notion, it opens a field for the 

 horticulturist to produce hybrid plants which perhaps could not 

 be obtained by seed. It is asserted, that, long after the bud on 

 the graft had perished, other small buds formed themselves round 

 it, all of which produced the true C. purpureus, except one, 

 from which proceeded the extraordinary hybrid. I apprehend, 

 that, if attention had been paid to this phenomenon, it would 

 have been found that the bud which produced it was formed 

 exactly at the junction of the bark of the two species, and that 

 the two contributed equally to its formation. A similar effect 

 might perhaps be expected also from a bud formed where the 

 mere bark of the graft is in contact with the wood of the stock. 

 Every bud on a tree is an individual ; and, if the graft and the 

 stock from any peculiar circumstances contribute equally to the 

 formation of a new bud, the individuality of that bud may be 

 expected to partake of their joint natures, as much as that of 

 the plant which is raised from hybrid seed. Let it therefore be 

 the object of gardeners who wish to obtain new plants analogous 

 to the C. Adara^", to kill the bud of the graft after a perfect 

 union has taken place, and to try to force the plant to break 

 again from the seam or edge of the bark that has been inserted. 

 Unless the bud shall be formed on the very seam, or where the 

 bark inserted is thin, so that the bud shall have taken its rise 

 from the contributive powers of the two plants, a new formation 

 cannot be expected. 



The circumstances attending the growth of C. Adam? are very 

 singular. Upon your tree one branch had reverted nearly to 

 the type of the laburnum, and another nearly to that of C. pur- 

 pureus, while the central shoots retained the hybrid character ; 

 but, on close observation, neither the leaves nor the flowei's of 

 the two branches, which had so reverted to the elements of the 

 parents, were precisely similar to them ; both however had ac- 

 quired fertility, while the central shoots continued sterile. From 

 the seed produced on the yellow-flowering branch, several plants 



