December 22, 1898] 



NA TURE 



179 



paratively uniform in character, that they are specifically 

 distinct from both parents. 



Generic Hybrids. 



Of the 500 primary hybrids on record, about loo are 

 generic hybrids, i.e. the parents belonging to different 

 genera. In this respect alone these hybrids are in- 

 teresting, though no doubt the systematic botanist views 

 them with mixed feelings. It is not so long since 

 generic hybrids were looked upon as anomalies, some 

 of the older naturalists even regarding them as im- 

 possible, and forthwith proceeded to beg the whole 

 question by classing those genera which were fertile 

 with one another as species of one. Orchid growers, 

 at all events, have almost ceased to regard generic 

 hybrids with curiosity, familiarity with them having bred 

 a certain amount of indifference. 



A list of the generic hybrids on record up to the end 

 of 1897, together with a diagram showing how twenty- 

 si.x different genera have been linked together by arti- 

 ficial hybridisation, has been prepared by the writer and 

 was published in l\\& Join aai o{ the Royal Horticultural 

 Society (vol. xxi., .^pril 1898), and to which those 

 interested in the details of generic orchid hybrids may 

 be referred. 



Generally speaking, primary generic hybrids follow 

 the rule of specific hybrids in bearing the intermediate 

 characters of their parents, with a narrow range of vari- 

 ation. 



But there are a few remarkable exceptions to this rule. 



(1) Epiplironitis x VeitcJiii, a hybrid out oi Sophronitis 

 grandijlora (Lindl.) by Epidendruiii ?-adica/is {Va.v.). 



(2) Ef)i-Cattleya x inatutiiia., a hybrid out of Cailhra 

 Bowrinoiaiia (\'eitch) by Epidendruin radicans (Pav.) 



(3) Epi-Laelia x radico-piirpitrata, a hybrid out of 

 Laelia purpurata{\A\-iA\.) by F.pidendrum radicaiis{\'a.\.). 



(4) Epi-Laelia x Charlcsi^'orthii, a hybrid out of 

 Laclia cinnabarina (Lindl.) by Epidendru)n radicans 

 (Pav.). 



These four generic hybrids are very curious indeed, 

 inasmuch as all agree in reproducing the generic 

 characters only of the pollen parent Epidendrum, with- 

 out the slightest trace of the peculiar structure of the 

 seed-parents, Sophronitis, Cattleya and Laelia. Vet in 

 minor characters, in colour, form and size, the four 

 hybrids distinctly differ from one another and from their 

 Epidendrum parent. 



.\ close examination reveals the fact that these minor 

 differences correspond with the peculiar differences in 

 the parentage, thus showing that the crosses have really 

 been effected : yet at the same time it must be candidly 

 admitted that did ue not know the parentage, we could 

 never have determined it, so overwhelming is the in- 

 fluence of the predominant partner Epidendrum radicans. 

 It will, no doubt, be observed that E. radicans is the 

 pollen parent in each of the above cases. Curiously 

 enough, when this reed-like E. radicans is crossed with 

 the pseudo-bulbous E. litcllinum (Lindl.), ?, a similar 

 result is obtained, the offspring E. x radico-vitelliniiin 

 being scarcely distinguishable from the reed-like E. 

 radicans. Again, when the reed-like E. x O' Brienianiun 

 — itself a hybrid out of E. evcctuin (Hook, f.) by E. 

 radicans — is crossed with the pseudo-bulbous E. vitel- 

 lini/in, $,a similar result is obtained, the offspring being 

 reed-like in habit as in the pollen parent. Vet when the 

 reed-like E. radicans is crossed with other reed-like 

 species of Epidendrum, and again when the pseudo- 

 bulbous species of Epidendrum are crossed with species 

 of Laelia, in every case normal hybrids are produced 

 intermediate between their parents. 



Though we cannot pretend to unravel this tangled 



skein, yet, so far as experiments have been made, it 



seems quite clear that (i) the species of Cattleya, Laelia, 



Sophronitis, and the pseudo-bulbous species of Epiden- 



NO. I 52 I. VOL. 59] 



drum, when intercrossed, produce normal hybrids inter- 

 mediate in character. 



(2) The same result is obtained when the reed-like 

 species of Epidendrum are united with one another. 



(3) But when the reed-like species of Epidendrum are- 

 united with the pseudo-bulbous species of Epidendrum, 

 or with species of Cattleya, Laelia and Sophronitis, 

 abnormal hybrids are produced, having the essential 

 characters of the reed-like Epidendra. From these facts 

 it might easily be argued that a reed-like Epidendrum 

 was the ancestor not only of the pseudo-bulbous Epi- 

 dendra, but also of the more highly specialised genera 

 Cattleya, Laelia and Sophronitis. In that case the 

 pseudo-bulbous Epidendra would form an interesting 

 connecting link between the lowly reed-like Epidendra 

 and the gorgeous aristocratic Cattleya and Laelia. 



Prcpolent Generic Crosses. 

 Perhaps the strangest curiosity in the history of orchid 

 hybridisation is the remarkable prepotency of the genus- 

 Zygopetalum over the three genera Odontogiossum, 

 Oncidium and Lycaste, so far as experiments ha\e 

 been made. Zy<;(>petalunt Mac/cayi (Hooker) has been 

 crossed with four distinct species of Odontoglossum, viz. 

 O. Pescatorei (Linden), O. crispuin (Lindl.), O. grande 

 (Lindl.) and O. bictonense (Lindl.), also with one species of 

 Oncidium, O. ungiiiciilatiiiu, and one species of Lycaste, 

 L. SkinneriCLwiAX.^^hy more than one hybridist, and the 

 result has always been the same, namely Z}\i;opeta/!iiit 

 Mackayi pure and simple, without a trace of the peculiar 

 structure of the pollen parent in any case. This result is 

 very perplexing and exceedingly difficult to account for. 

 I have made careful inquiries into the details of all these 

 cases, and have satisfied myself that accidental self- 

 fertilisation is out of the question, the pollen of the mother 

 parent having been carefully removed in every case pre- 

 vious to pollination. Parthenogenesis, too, is evidently a 

 broken reed to lean upon, for the seedlings from the same 

 seed-pod differed among themselves in colour and other 

 minor characters, which would hardly have been the case 

 had they arisen from parthenogenetic seed-buds. Neither 

 is Z. Macicayi naturally prepotent over other species when 

 crossed, there being at least three cases to the contrary. 

 Nor is the genus Zygopetalum naturally prepotent over 

 other genera, as two distinct and intermediate hybrids 

 between Zygopetalum and Colax testify. As in the case 

 of the Epidendrum crosses, mentioned above, it may be 

 suggested that Zygopetalum is the ancestral genus of 

 Odontoglossum, Oncidium and Lycaste, and that the 

 characters of the ancestral genus remain latent in the 

 more recent genera, with the result that when the latter 

 are crossed with the former, the mixing of the germ- 

 plasms causes these original characters to dominate, 

 the outcome being a reversion to the ancestral genus 

 Zygopetalum. 



A rather interesting fact has come to light which 

 certainly lends colour to the above speculation : — The 

 seedling Odontoglossums, raised in the gardens of Baron 

 Rothschild, of Paris, during the first eighteen months of 

 their growth, are said to have resembled Zygopetalum 

 more than they did Odontoglossum. This coincides with 

 the established fact that living beings tend to resemble 

 their ancestors in the early stages of their development. 

 However, for the present we must suspend our judgment, 

 and wait patiently for further facts : it is to be hoped 

 that future experiments will throw more light upon these 

 curious generic crosses. 



Another curious fact in connection with generic crosses 

 may perhaps be of interest, and that is the remarkable 

 crosses between the East Indian species of Cypripedium. 

 and the South ."American species ; these two sections of 

 the old genus Cypripedium have recently been raised to- 

 generic rank, under the names of Paphiopedium and 

 Phragmipedium respectively, by .Mr. R. .\. Kolfe, of Kew, 



