390 



ANOMALOUS MODES, 



Chap. XI. 



P> 



arisen. In a bed of seedlings from 0. elongatus, which grew near to G. pur- 

 pureus, and was probably fertilised by it, through the agency of insects 

 (for these, as I know by experiment, play an important part in the fertilisa- 

 tion of the laburnum), the sterile hybrid C. purpureo-elongatus appeared. 93 

 Thus, also, Waterer's laburnum, the C. alpino-laburnum, 94 spontaneously 

 appeared, as I am informed by Mr. Waterer, in a bed of seedlings. 



On the other hand, we have a clear and distinct account given by 

 M. Adam, who raised the plant, to Poiteau, 05 showing that 0. adami is not 

 an ordinary hybrid. M. Adam inserted in the usual manner a shield 

 of the bark of 0. purpureas into a stock of 0. laburnum ; and the bud lay 

 dormant, as often happens, for a year ; the shield then produced many buds 

 and shoots, one of which grew more upright and vigorous with larger 

 leaves than the shoots of 0. purpureas, and was consequently propagated. 

 Now it deserves especial notice that these plants were sold by M. Adam, 

 as a variety of 0. purpureas, before they had flowered; and the account 

 was published by Poiteau after the plants had flowered, but before they 

 had exhibited their remarkable tendency to revert into the two parent- 

 species. So that there was no conceivable motive for falsification, and 

 it is difficult to see how there could have been any error. If we admit 

 as true M. Adam's account, we must admit the extraordinary fact that two 

 distinct species can unite by their cellular tissue, and subsequently produce 

 a plant bearing leaves and sterile flowers intermediate in character between 

 the scion and stock, and producing buds liable to reversion; in short, 

 resembling in every important respect a hybrid formed in the ordinary 

 way by seminal reproduction. Such plants, if really thus formed, might 

 be called graft-hybrids. 



I will now give all the facts which I have been able to collect illustrative 

 of the above theories, not for the sake of merely throwing light on the 

 origin of 0. adami, but to show in how many extraordinary and complex 

 methods one kind of plant may affect another, generally in connection 

 with bud-variation. The supposition that either C. laburnum or pur- 

 pureas produced by ordinary bud-variation the intermediate and the 

 other form, may, as already remarked, be absolutely excluded, from 

 the want of any evidence, from the great amount of change thus implied, 





93 Braun, in « Bot. Mem. Bay Soc.,' 

 1853, p. xxiii. 



94 This hybrid has never been de- 

 scribed. It is exactly intermediate in 

 foliage, time of flowering, dark strise at 

 the base of the standard petal, hairi- 

 ness of the ovarium, and in almost every 

 other character, between C. laburnum 

 and alpinus ; but it approaches the 

 former species more nearly in colour, 

 and exceeds it in the length of the 

 racemes. We have before seen that 

 20-3 per cent, of its pollen-grains are 

 ill- formed and worthless. My plant, 



though growing not above thirty or forty 

 yards from both parent-species, during 

 some seasons yielded no good seeds; 

 but in 1866 it was unusually fertile, and 

 its long racemes produced from one to 

 occasionally even four pods. Many of 

 the pods contained no good seeds, but 

 generally they contained a single appa- 

 rently good seed, sometimes two, and 

 in one case three seeds. Some of the 

 seeds germinated. 



95 'Annales de la Soc. de Hort. de 

 Paris/ torn, vii., 1830, p. 93. 



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