414 GRAFT-HYBRIDS. Chap. XL 



branches on this tree have repeatedly and suddenly reverted to the 

 two parent- species in their flowers and leaves. To behold mingled 

 on the same tree tufts of dingy-red, bright yellow, and purple 

 flowers, borne on branches having widely different leaves and 

 manner of growth, is a surprising sight. The same raceme some- 

 times bears two kinds of flowers; and I have seen a single flower 

 exactly divided into halves, one side being bright yellow and the 

 other purple ; so that one half of the standard-petal was yellow and 

 of larger size, and the other half purple and smaller. In another 

 flower the whole corolla was bright yellow, but exactly half the 

 calyx was purple. In another, one of the dingy-red wing-petals had a 

 narrow bright yellow stripe on it; and lastly, in another flower, 

 one of the stamens, which had become slightly foliaceous, was half 

 yellow and half purple; so that the tendency to segregation of 

 character or reversion affects even single parts and organs. 91 The 

 most remarkable fact about this tree is that in its intermediate 

 state, even when growing near both parent-species, it is quite 

 sterile ; but when the flowers become pure yellow or pure purple 

 they yield seed. I believe that the pods from the yellow flowers 

 yield a full complement of seed; they certainly yield a larger 

 number. Two seedlings raised by Mr. Herbert from such seed 92 

 exhibited a purple tinge on the stalks of their flowers ; but several 

 seedlings raised by myself resembled in every character the common 

 laburnum, with the exception that some of them had remarkably 

 long racemes: these seedlings were perfectly fertile. That such 

 purity of character and fertility should be suddenly reacquired 

 from so hybridised and sterile a form is an astonishing pheno- 

 menon. The branches with purple flowers appear at first sight 

 exactly to resemble those of C. purpureus ; but on careful com- 

 parison I found that they differed from the pure species in the 

 shoots being thicker, the leaves a little broader, and the flowers 

 slightly shorter, with the corolla and calyx less brightly purple : 

 the basal part of the standard-petal also plainly showed a trace of 

 the yellow stain. So that the flowers, at least in this instance, had 

 not perfectly recovered their true character; and in accordance 

 with this, they were not perfectly fertile, for many of the pods 

 contained no seed, some produced one, and very few contained as 

 many as two seeds ; whilst numerous pods on a tree of the pure C. 

 purpureas in my garden contained three, four, and five fine seeds. 

 The pollen, moreover, was very imperfect, a multitude of grains 

 being small and shrivelled; and this is a singular fact; for, as we 

 shall immediately see, the pollen-grains in the dingy-red and sterile 

 flowers on the parent-tree, were, in external appearance, in a much 



91 For analogous facts, see Braun, forschender Freunde,' June, 1873, p. 



* Itrjuvenescer.ce,' in ' Ray Soe. Bot. 63. 



Mem.,' 1853, p. 320; and ' Gard. 92 ' Journal of Hort. Soc.,' vol. ii 



Chron.,' 1842, p. 397 : also Braun, 1847, p. 100. 

 in ' Sitzunzsberichte der Ges natur- 



