448 



NA TURE 



[September 5, 1901 



from Digitalis ambigua (Scrophulariaceas) by pollen of 

 Sinningia spcciosa (Gesneraceffi) is described. This, 

 then, was a biordinal hybrid. 



Fertile hybrids, the e.xistence of which was once denied, 

 are now too numerous to admit of further doubt. Mr. 

 Hurst, /.f., cites the occurrence of such plants in ninety 

 distinct genera and only four in which the hybrids are quite 

 infertile. Ninety per cent, of some forms of tuberous 

 Begonias come true from seed, as is recorded in Mr. 

 Lynch's excellent paper on the evolution of plants in the 

 Journal of the Royal Horticultural .Society (vol. xxv. 

 igoo, p. 24). In that paper numerous illustrations are 

 adduced to show that some garden hybrids, perhaps we 

 might say a large proportion, " come true from seed," 

 that is, the parental characters are reproduced in the 

 progeny as markedly as in the case of any so-called 

 species. Bigeneric hybrids are sometimes equally fertile. 

 For instance, there are two I ridaceous genera, Montbretia 

 and Tritonia, so distinct one from the other that they have 

 always been considered as separate genera. Now the 

 plant called Mivitlnrtia crocosDiiaeflora x by Lemoine 

 was raised by that eminent French gardener between 

 Tritonia ai/ri'a, which furnished the pollen, and Mont- 

 Im-tia Pottsii as the female parent. This is what M. E. 

 Lemoine says in the volume to which we have just 

 referred (p. 128) ; — 



" It is generally admitted by all that hybrids are, as a 

 rule, either absolutely barren or at most produce descen- 

 dants as lacking in number as they are also in vigour 

 and in reproductive qualities. Now Montbretia crocos- 

 niiacflora X is a hybrid, and by no means an ordinary 

 hybrid, for it is one of the very small group of bigeneric 

 hybrids, its two parents ranking as species of different 

 genera, and yet it has given birtli to a long line of 

 vigorous and fertile plants." This hybrid produces seed 

 naturally, but as the progeny is almost identical with the 

 paient forjn there is no particular object in the gardener 

 raising such seedlings. But when the flowers of this 

 hybrid are pollinated, by pollen taken from either of the 

 original plants, then modification sets in and these modi- 

 fications have become fixed (see p. 129). 



Chionoscilla x. The hybrid genus between Chionodoxa 

 and Scilla, which occurs spontaneously when the two 

 plants are grown together, is reported by Hurst to have 

 produced fertile seeds. 



Whether the facts that some of the so-called genera 

 not only interbreed but " come true from seed " are to be 

 taken as proofs against their autonomy as separate 

 genera or not is a point of the highest interest, to which we 

 can only allude, but which we cannot here discuss. We 

 must be permitted for our present purpose to set aside 

 theoretical considerations and to look on both species 

 and genera as convenient subdivisions necessitated by 

 the requirements of classification, but which, though 

 probably so, are not yet proven to be phylogenetically 

 '■ natural." All that we are concerned here to assert is 

 that the gardener has succeeded in producing forms as 

 distinct one from another as, often far more so.than, those 

 which we call species, and even genera, and which 

 physiologically as well as morphologically " behave " in 

 the same way that species do. 



Tuberous Begonias furnish a case in point. They are 

 no older than, scarcely so old as, the middle of the last 

 century. Their history is perfectly well known. They 

 have grown, as it were, under our very eyes. Were it 

 not so there is no botanist who, seeing them for the first 

 time, but would call them new species and think himself 

 very fortunate in getting new species with such definite 

 and easily recognisable marks of distinction. A dis- 

 tinguished French botanist, the late M. Fournier, even 

 constituted a new genus, Lemoinea, to receive some of 

 these widely divergent forms. 



But, some will say, these creations of the gardener's 

 skill are not permanent ; alter the conditions and they 



NO. 1662, VOL. 64] 



will disappear. Moreover, they can only be propagated 

 by division and not by seed. Were these objections uni- 

 versally true they would, of course, be fatal to our conten- 

 tion. But they are not universally true, and those that 

 are true are just as applicable to natural species. Some 

 at least, as we have seen, have a high degree of per- 

 manence, and many are capable of reproduction from seed. 

 It must not be supposed that these hybrid productions 

 are all of artificial origin. So far back as 1852, WeddeH 

 enumerated, in the Annates des Sciences Naturelles, 

 numerous natural bigeneric hybrids, and, of course, 

 hybrids between species are now known to occur fre- 

 quently among wild plants. But what is very interesting 

 in this connection is the fact that gardeners have, 

 o\er and over again, demonstrated the hybrid nature 

 of certain wild plants by actually producing them 

 artificially. The younger Reichenbach, from his great 

 knowledge and experience, asserted that several orchids 

 examined by him were of hybrid origin. He arrived 

 at his conclusions solely from the observation of morpho- 

 logical characters. But Veitch and many others have 

 since actually created in their orchid houses, by means of 

 cross fertilising the two species, the same form that occurs 

 in nature. They have proved by demonstration what 

 Reichenbach merely conjectured from appearances. An 

 enumeration of these orchid hybrids that have been pro- 

 duced in gardens is given by Mr. Rolfe in vol. xxiv. of 

 the Journal of the Royal Horticultural Society, p. 188. 

 Years before Reichenbach, Dean Herbert came to a 

 similar conclusion as to the hybrid nature of certain 

 Pyrenean narcissi, and he too proved the accuracy of his 

 opinion by producing the hybrid form by artificial means. 

 In our own times, Engelheart is doing the same sort of 

 work and arriving at the same conclusions. 



In the last class of cases, the gardeners have, as we 

 have said, succeeded in reproducing the identical form 

 that occurs in nature, and that form, of course, cannot be 

 considered in any sense as a 7iew garden-plant. But in 

 the other cases mentioned, such as the Begonias, the 

 Streptocarpus, the Clematis, &c., forms have been pro- 

 duced which have not, and could not have, any counter- 

 part in nature. Some of the Andine Begonias very 

 possibly hybridise naturally because they grow in proxi- 

 mity, or at no very great distance from each other. But 

 what are we to say to the new " race " or " species," as we 

 might term it, produced in gardens by fertilising the 

 descendants of these South American Begonias with one 

 discovered in Socotra by Prof Bayley Balfour ? It is hard ' 

 to conceive of the possibility of a natural hybrid in this 

 case, but, as artificially produced by the gardener, it is 

 one of the greatest ornaments of our hot-houses and 

 much more distinct from other "species " than most of 

 the South .American forms among themselves. It is true 

 that in this case, up to this time, the flowers have been 

 mostly sterile, but there are not wanting indications that 

 the sterility may be naturally replaced by fertility, whilst 

 it is certain that the gardener will discover the means to 

 counteract the present nearly barren condition. 



It would be easy to multiply instances wherein the 

 gardener has produced new forms morphologically, and 

 in some cases physiologically, worthy of specific or' even 

 of generic rank, but it is unnecessary to cite more, as the 

 fact admits of no dispute. We have alluded to them 

 here for the sake of illustrating one category of "new 

 garden plants." 



A point of much practical importance arises with 

 reference to the names that should be given to these 

 garden productions. The Kew list to \yhich we have 

 referred takes the names as they are published in the 

 gardening journals, which in their turn copy them from 

 the labels or the catalogues of the horticulturists. The 

 journals are duly cited in the Kew list, but in no case is 

 the author's name mentioned. 



