Differences in Reciprocal Crosses

There are at least two distinct mechanisms for the differences: Cytoplasmic Inheritance and Hetero-Fertilization. These are not mucuatlly exclusive, as both may operate at the same time.

Rivers: The Rose Amateur's Guide (1846) p. 44
Hybrids produced from the French rose impregnated with the China rose, are not of such robust and vigorous habits as when the China rose is the female parent; but, perhaps, this is an assertion scarcely borne out by facts, for the exceptions are numerous, and, like many other variations in roses and plants in general, seem to bid defiance to systematic rules.

Nicolas: Hybridizing Rose Species (1933)
...my experiences of many years concur with Mallerin's of France, Lambert's of Germany, Dot's of Spain, and other practitioners, that the species is more easily and quickly "cracked" when used as pollen parent; its imprint at the first generation is generally more subdued, or to be more correct, the percentage of the mother type, with, of course, a more or less pronounced species influence, will be much larger than the species type, and these mother types will save time in bringing the desired finished product. For instance, a cross of Hortulanus Budde x R. Moyesi gave me slightly modified Hybrid Tea types where Moyesi was only recognized by the weird red single blooms and smaller foliage, while one almost totally mother type revealed the pollen parent only by the queer bottle shape of Moyesi fruits. The reciprocal cross (R. Moyesi x Hortulanus Budde) produced plants almost as uncouth and crude as Moyesi.

Proceedings 14th International Horticultural Congress, p. 359 (1955)
Rosa moyesii appears to transmit the bright red color only through the ovum and not by the pollen (S. G. A. Doorenbos, The Netherlands).

Journal of Horticulture and Home Farmer (May 23, 1907)
Breeding from the Baby Rambler Rose.
A number of cross-bred seedlings, grown from Baby Rambler [Mme Norbert Levavasseur], are disappointing in that none turns out to be constant-blooming, though largely pollenised with ever-blooming kinds, says Dr. Van Fleet in "Rural New Yorker." All came near to the Crimson Rambler type, regardless of the habit of the pollen parent, and will probably develop into tall-climbing annual bloomers. When pollen of Baby Rambler, which has the continuous flowering Gloire des Polyanthes as one parent, is used on the stigmas of annual-blooming Ramblers of Wichuraiana hybrids, very dwarf ever-blooming plants result in large proportion, and something may perhaps be done to develop a useful group, of which Baby Rambler will likely remain the type.

Journal of Heredity, 20:304-307 (1929)
Rosa Gigantea And Its Hybrids
H. Cayeux
The second cross, that is to say, the Tea rose x R. gigantea, produced several very excellent and beautiful hybrids, chiefly characterized by their soft coloring, their great profusion of blooms, and their greater resistance to cold.

Wichura on Hybrids (1866) p. 73
Wichura confirms Gaertner in the assertion that where hybrid pollen is used for the impregnation of simple or complicated hybrids, as also in pure species, there is a great predominance of individual forms, while hybrid ovules impregnated by the pollen of pure species, even in the most complicated combinations, give very uniform products.

Text-book of Botany (1875)
Julius Sachs
The hybrid is possessed of external characters intermediate between those of its parent-forms, usually nearly half way between; less often it resembles one of the parent-forms more nearly than the other, and this is more often the case with variety-hybrids than with species-hybrids. It follows that in reciprocal hybrids from the species A and B, the hybrid A B is generally similar externally to the hybrid B A, though the two forms may differ somewhat internally. Thus, according to Gärtner, the hybrid Nicotiana paniculato-rustica is more fertile than the reciprocal hybrid Nicotiana rustico-paniculata*. An internal difference between reciprocal hybrids is also shown by the fact that one is more variable than the other; thus, according to Gärtner, the progeny of Digitalis purpureo-lutea is more variable than that of D. luteo-purpurea, the progeny of Dianthus pulchello-arenarius more variable than that of D. arenario-pulchellus.

*In this mode of designating hybrids, the name of the male parent-plant stands first; thus Nicotiana rustico-paniculata is the product of the fertilisation of N. paniculata by the pollen of N. rustica.

Gardeners' Chronicle p. 529 (April 27, 1889)
THE ORIGIN OF THE GARDEN AURICULA.— We have been favoured with the following communication, accompanied by specimens, which we regret did not reach us till after the Auricula meeting of the Royal Horticultural Society:— "The question of the probable origin of the garden Auricula has been several times mentioned in your columns. Some years ago I brought two Primulas from the Alps, Primula Auricula lutea and Primula viscosa, a very pretty pink variety. I have crossed these both ways, and when the yellow kind is the seed-bearing parent, the produce is an inferior alpine garden Auricula; when the pink kind is the seed-bearer, a very pretty purple hybrid is produced, with very little variation in the character of the different seedlings, though they are quite distinct from either parent. I enclose specimens of the parent plants and of the hybrids, from which you will see that in those whose seed-parent was P. A. lutea there are several gradations of colour. I think such specimens as these would, by careful selection, soon yield many, if not all, the shades of colour now cultivated in our gardens. — James Ellis."

The Gardeners' Chronicle 19: 727 (June 13, 1896)
During the last two decades a most interesting kind of tufted Pansy has been raised, viz., the Rayless Violas, which have flowers of but one colour, free from the ordinary dark rays or streaks, whence their name. The first time I find any mention made of them is in 1881, when in The Garden W. Robinson related that at Laing's of Stanstead Park Nurseries, he saw two kinds of such Pansies (Hybrida alba and Golden Queen of Spring). Not until the very last years of the eighties did they become more widely known. Then appeared Charles Stuart's well-known Violetta, a very small-flowering almost pure-white fragrant tufted Pansy, the product of a cross between Viola cornuta, L, as the female parent, and the Pansy Blue King as the male plant. Dr. Stuart lays special stress on the fact that in hybridisation with V. cornuta it should be used as the female, and the Pansy chosen for the occasion as the male plant, if a progeny be desired resembling V. cornuta as regards perfume and perennial duration. Violetta has in turn produced a numerous offspring (among others, the celebrated Sylvia), which, together with other rayless tufted Pansies, play an important part in the shows of the Scottish and English Pansy societies.

Hurst: Notes on Some Curiosities of Orchid Breeding (1898)
Laelia anceps pollen seems invariably to cut down time needed to ripen pods of Cattleya labiata group by about six months; while the pollen of C. labiata does not appreciably lengthen the time needed by L. anceps pods to ripen .... Broughtonia sanguinea, which both with its own and with foreign pollen ripens its seeds in one-and-a-half to two months, has power to quicken the ripening of C. Bowringiana, with which it gave good seed in eight-and-a-half months."

Breeding Dendrobium Orchids in Hawaii pp. 69-70 (1999)
Haruyuki Kamemoto, Teresita D. Amore, Adelheid R. Kuehnle
Dendrobium canaliculatum
D173-2 and D129
McConnell and Kamemoto (1983) observed large differences in plant height, number of pseudobulbs, and yield between progenies involving reciprocal crosses of D. canaliculatum accessions, D173-2 and D129 (Table 7.4). Chromosome counts of both parents and all offspring were 2n=38. Therefore the differences between the two reciprocal progenies were not due to differences in chromosome numbers as with the previous two examples, but are probably cytoplasmic effects.
    Dendrobium canaliculatum D137-2 was introduced from Lae, Papua New Guinea, whereas D. canaliculatum D129 was obtained from a local orchidist and is probably of Australian origin. The differences encountered emphasize the need to consider the transmission of cytoplasm as well as chromosomes.

American Naturalist 32: 355 (1898)
Dissimilar Reciprocal Crosses. — It has been observed in many cases that the two hybrids A x B and B x A are dissimilar. In the current Heft of the Jenaische Zeitschrift is an interesting note by the late Fitz Müller-Desterro, serving to explain this phenomenon in a single case, the hybrid of Ruellia formosa and R. silvaccola. The parent flowers differ in that those of R. formosa are a dark, luminous red, while those of R. silvaccola are a clear, faint red. The hybrid R. silvaccola x formosa is of a beautiful red, more like the red of R. formosa than of R. silvaccola; and R. formosa x silvaccola is of a cloudy mixed color, with more or less extensive smutty blotches. The difference of color is due to the fact that the egg cell only, and not the male cell, transmits the chromatophores upon which the color depends; hence, the hybrid R. silvaccola x formosa received chromatophores from silvaccola only, while formosa x silvaccola received them from formosa only. (This result does not, however, fully explain the observed facts of color in the hybrid.) The important conclusion is now drawn that in this case the qualities of the hybrid depend, not alone on the germ plasm in a strict sense, but also on certain living included particles.

Lemoine: Hybrid Lilacs (1900)
It is very probable that this Varin Lilac type, of which the leaves are wider than those of any hybrids, has been produced by the fortuitous fertilisation of the common Lilac by the laciniate Persian Lilac, since Varin has only thought of sowing seeds of the common Lilac. It would therefore be a hybrid inverse to mine, and this difference of origin would be translated into a difference of width in the leaves.

Duval: Gloxinias and Their Artificial Fertilisation (1900)
    Some types have been fixed in such a way that it becomes practically impossible to alter them. I have obtained a Gloxinia named 'Boule de Feu,' the very brilliant carmine-red of which has defied the intermixture of every other colour.
    This plant, which had for its great-grandfather the Gloxinia 'Mina' of Van Houtte, has served us as a mine of colours for some years, the richness of its tints being inexhaustible. Everything I fertilised with this plant assumed superb colours, blues, pinks, magenta, violets; all these plants, impregnated by the Gloxinia 'Boule de Feu,' produced remarkable colours and of incomparable brilliancy.
    But when I desired to fertilise my 'Boule de Feu' by other coloured varieties, two-thirds of the produce were 'Boule de Feu,' and the remainder of very little value.

Gardeners' Chronicle (3rd series) 31: 229 (April 5, 1902)
THE HYBRIDISATION OF CISTUS.— Self-fecundation is impossible with many species of Cistus, although the pollen and the ovules are perfect, and fertilise the flowers of other individuals which allow themselves to be fertilised by them. The pollen of Cistus monspeliensis fecundates most of the white-flowered species of Cistus, while it is with difficulty fertilised by them; of 200 fecundations attempted on this species, one plant only did well. Other species manifest the same differences in their aptitude to fecundate, or to be fecundated. In crossings where the role of the parents is interchanged, the productions are often quite similar; sometimes they are not similar. C. ladaniferus crossed by C. hirsutus forms an erect shrub, C. hirsutus crossed by C. ladaniferus forms a low plant like the mother.*
*Ed. Bornet, Notice sur les Travaux Scientifiques, Paris, 1886. Bull. Soc. Bot. France, xlvi. (1899) p. cxci.

Vilmorin: The Story of the Gladiolus and its Garden Forms (1904)
M. Krelage gives G. turicensis (obtained by M. Froebel) as identical with G. Childsii of M. Max Leichtlin. Now, according to the information which I have gathered, G. Childsii is a hybrid between G. gandavensis and G. Saundersii. If, therefore, the order in which M. Krelage gives the parents of G. turicensis is exact (G. gandavensis x G. Saundersii), these two Gladioli are the issue of the same parents, but by crossings operated in inverse order. In any case it is G. Childsii, and not G. turicensis, which has helped to produce this beautiful novelty of large size and brilliant coloring.

Cornell Extension Bulletin 10: 2591 (Dec. 1916)
Gladiolus Studies - II
Alfred C. Hottes
With gladiolus the results seem to differ from the above-mentioned cases, perhaps due to the extreme hybridity. Lemoine obtained Gladiolus nanceianus by crossing G. Saundersii and G. Lemoinei, G. Saundersii being the seed parent. The reverse cross gives many fine flowers, but none so rich in color nor so characteristic in shape. G. Colvillei is the result of crossing G. cardinalis on G. tristis concolor, and the reciprocal cross is not mentioned as being identical. In R. T. Jackson's hybrids between G. gandavensis and G. purpureo-auratus, the latter was used as the male parent; the reverse order gave little success, but no notes were kept.

Halsted: Reciprocal Hybrids of American and Chinese Eggplants (1906)
The reciprocal of the above hybrid was represented by eleven thrifty plants, resulting from the union of the "Scarlet Chinese" upon the "Dwarf Purple," the record fraction here being 25/6, that is, the reverse of the last. The plants were in full bloom upon August 9th, and the record shows that the plants were practically the same as those of 6/25, above described, excepting in the matter of size, they being uniformly over a third larger (four feet).

Third International Conference on Genetics (1906)
Hybrids among the Amarylliae and Cactaceae ...

Arthington Worsley
Phyllocactus Cooperi (white) x P. Ackermanni (red) gave nothing but reds and pinks. Reverse cross gave 33 reds, 14 pinks, 3 orange, and 17 magenta. The appearance of orange is easily accounted for. The blue shade is perhaps due to a colour-erraticism latent generally in P. Ackermanni, but almost typical of several Cacti. Even in P. Ackermanni the stigma is always bright purple.

Report of the Third International Conference 1906 on Genetics p. 87.
Specimens Exhibited by Dr. John H. Wilson, St Andrews University, Scotland.
4. Digitalis lutea x D. purpurea, D. lutea x D. purpurea alba, and D. purpurea alba x D. lutea. These specimens showed that the hybrids having the white foxglove as a parent were more vigorous than those having the purple foxglove, and further that the reciprocal crosses between the white foxglove and D. lutea differed in respect of form and colour of the flower.

Journal of Genetics 2: 71-88 (1912)
Species Hybrids of Digitalis
W. Neilson Jones, M.A.
The cross between D. purpurea and D. lutea has been re-investigated by J. H. Wilson and described in the Report of the 3rd International Conference on Genetics (1906). Briefly, the facts concerning the hybridising of these two species are as follows:
    It was found much easier to effect the cross when D. purpurea was used as pollen parent. The reciprocal crosses difffered from one another as to their flowers, in each case more closely resembling the seed-parent. The hybrid having D. purpurea as seed-parent had larger and wider flowers of a rose colour although the D. purpurea used was a white flowered variety without coloured spots (from which it was concluded, incidentally, that colour may be latent in a white foxglove). In the cross in which D. lutea was used as seed-parent the flowers were narrower and in colour creamy-yellow or almost white with a pale rose flush, even when a purple D. purpurea was used. The flowers of both hybrids had purple spots inside the corolla tube.
    In a subsequent series of experiments Wilson found that the F1 plants of both hybrids varied considerably among themselves as to flower colour. This was possibly due to the use of an impure strain.
    The reciprocals were indistinguishable until they flowered.
    No fertile seed was obtained from either hybrid.

New Jersey State Agricultural Experiment Station (1909)
Byron D. Halsted, Sc.D.
Pea Crosses
Observations: (1) A great majority of reciprocals are dissimilar. (2) The female parent seems to have a greater influence on the blend in period of maturity, height of plant and prolificness. (3) Blends may deviate in a unum [i.e., unit character] even when the parents are similar in that unum; the deviation is greater the more the reciprocals tend to become dissimilar.

White Blackberries (1914)
Luther Burbank
It was to be expected, therefore, that the cross between the Lawton and the "white" berry would result in producing all black stock closely resembling the Lawton; and such was indeed the result.
    But the Lawton also imparts its good qualities to hybrids when its pollen is used to fertilize the flowers of other varieties. As a general rule it is my experience that it makes no difference which way a cross is effected between two species of plants. The pollen conveys the hereditary tendencies actively, and so-called reciprocal crosses usually produce seedlings of the same character.
    That is to say, it usually seems to make no practical difference whether you take pollen from flower A to fertilize flower B, or pollen from flower B to fertilize flower A.
    This observation, which was first made by the early hybridizers of plants more than a century ago,—notably by Kölreuter and by Von Gartner,— fully confirmed by my observations on many hundreds of species. Nevertheless it occasionally happens that the plant experimenter gains some advantage by using one cross rather than the other. In the present case it seemed that by using the Lawton as the pollenizing flower, and growing berries on the brownish white species, a race was produced with a more pronounced tendency to vary.
    Still the plants that grew from seed thus produced bore only black berries in the first generation, just as when the cross was made the other way. It thus appeared that the prepotency of the Lawton manifested itself with full force and certainty whether it was used as the staminate or as the pistillate flower.
    When the flowers of this first filial generation were interbred, however, the seed thus produced proved its mixed heritage by growing into some very strange forms of vine. One of these was a blackberry that bloomed and fruited all the year. This individual bush, instead of dying down like others, kept growing at the top like a vine or tree, and when it was two or three years old it was so tall that a step-ladder was required to reach the fruit. Its berries, however, were rather small, soft, and jet black in color.

Jour. Royal Hort. Soc. Vol. LVII. Part 1. January 1932
The genus Amaryllis including its bi-generic and other hybrids and crosses.
by A. Worsley
Mr. John Hoog, of Messrs. Van Tubergen, and myself have both raised hybrids between Amaryllis and Brunsvigia Josephinae. Hoog raised hybrids both ways, and those he raised on Brunsvigia are very dissimilar plants from those raised on Amaryllis, thus perplexing (in this single instance at least) those pundits who declare that whichever way a hybrid is raised it must bear the same name, and perplexing also those who deal in these plants, and who must follow the accepted nomenclature however much it may be contradicted by the appearance of the hybrids themselves.

Herbertia (1936)
History of Hippecoris Garfieldii
Robert T. Van Tress
From 68 bulbs of Hippeastrum vittatum hybrid x Lycoris aurea 40 or 59% produced 3 or more flower-scapes with an average of 4 flowers each at an average height of 30.5 inches. There were 7 bulbs that produced 4 scapes each, resulting in a total of 16 flowers per plant. These blooming periods came at fairly regular intervals—namely during January, February, July and August. However, there were some flowers visible from December 8th until the first part of September with the exception of a few weeks in April. The colors varied from lighter orange red through light orange red to dark orange red. The dominance of the pistillate parent (a red amaryllis) was indicated by the size, color and kind of seed produced.
   50 bulbs of Lycoris aurea x Hippeastrum vittatum hybrid produced only 14% with 3 flower-scapes, the average number of flowers being only 3 and the average height 28 inches. These plants were uniformly less vigorous and flowers much lighter in color varying from orange to light orange red and being smaller in size. The dominance of Lycoris aurea was apparent in the color and size but none of the botanical characters such as round seeds which seems unusual.

Jones, D. F.: Reciprocal Crosses. Maize Newsletter Issue 17 (1943)
2. Reciprocal crosses between inbred strains may show small differences in amount of growth in early stages after germination due to differences in embryo size or seed condition. These differences usually disappear by the time the plants flower. In crosses of a Rice pop inbred with very small seeds and a yellow dent inbred with large seeds marked differences were obtained in the reciprocals. Three weeks after planting the dent parent was nearly twice as tall as the pop parent and proportionally larger in overall size dimensions. At this stage the dent x pop F1 is taller than the dent parent while the pop x dent F1 occupies an intermediate position between the two parents. The hybrids and parents tassel and silk in the same order as their initial embryo weights: (1) dent x pop, (2) dent parent, (3) pop x dent, (4) pop parent. At the end of the season the two reciprocal crosses are equal in production of grain and in height and both are taller and more productive than either parent. Production of grain of the hybrid is about 15 times that of the pop parent and nearly twice as much as the dent. Both reciprocals reach full maturity at about the same time but the one that is smaller at the start continues rapid growth longer to reach eventually the same height and production of grain in approximately the same length of time. Since one of the hybrids starts smaller after germination and ends up larger in the amount of material produced than the larger parent, in the same period of growth, one is growing at a faster rate than the other.
     The parents and reciprocal crosses also differ in the number of tillers. The dent inbred averages .03, dent x pop 2.06, pop x dent 1.24, and pop inbred 2.83 tillers per plant. The larger number of tillers is shown by the hybrid with the non-tillering seed parent. In these reciprocal crosses having the same genic constitution, tillering is an expression of initial vigor large enough to overcome any differences in maternal effect. Differences that may exist in the cytoplasm of these two widely diverse reciprocal crosses have no effect on the final reaction product between the external environment and the nuclear construction of the hybrids.

Wide Hybridization in Plants pp. 359-364 (1960, English trans. 1962)
M. K. Gol'dgauzen
It is noteworthy that, in crosses between C. edulis and C. colocynthis as in crosses with C. colocynthoides, the length of the vegetative period depends to a considerable degree on the respective reciprocal crosses (Table 4).

Crossed species Number of days from
fruit set to maturation
C. edulis x C. colocynthoides 52
C. colocynthoides x C. edulis 68
C. edulis x C. colocynthis 60
C. colocynthis x C. edulis 94

Genetics Today, 1963 p. 242-243
13.94. Some Biochemical and Physiological Properties of Plant Reciprocal Hybrids.
S. I. Issaev and V. V. Vartapetyan (Moscow, U.S.S.R.)
     Numerous investigations on morphological, physiological and biochemical properties of reciprocal hybrids of woody plants (apple-tree) as well as other plants (tomato) were carried on since 1935 in I. V. Michurin Horticulture Institute and since 1955 in Moscow State University, Chair of Genetics.
     The choice of the maternal plant often determines the difference in properties of the hybrid generation derived from the same pair of initial forms.
     Initial varieties influence more actively the expression of properties of the hybrid generation, when they are used in the initial pair as maternal plant.
     Hence it was demonstrated, that crossing of frost-resistent (northern varieties) and frost-sensitive (southern varieties) of apple-trees produced more frost-resistant hybrid F1, in the case where the northern variety was used as maternal plant.
     Content of sugar and vitamin C in fruits of reciprocal tomato hybrids was higher in the case, where the variety with high level of these substances was taken as maternal plant. The choice of the maternal plant influenced also the degree of heterosis. Heterosis of a certain property increased, when the maternal plant of the pair was characterized by the same property.
     Special experiments were carried out with grafts and the reciprocal crosses on these. These experiments showed that additional influence of the maternal plant on the properties of the progeny could be explained mainly by metabolic action of plant plastic substances on the embryo, which developed on this plant.
     The obtained data could be valuable in a scientific as well as in a practical sense, namely for selection and seed-growing.

Sager: Cytoplasmic inheritance in Epilobium (1972)
Fig. 6.6. Typical F1 plants resulting from reciprocal crosses between two species of Epilobium, E. luteum and E. hirsutum. The plant on the right, with stunted growth and sterile pollen, received its cytoplasm principally from the E. hirsutum parent, while the healthy plant on the left received its cytoplasm from the E. luteum parent.

ISHS Acta Horticulturae 56: Symposium on Juvenility in Woody Perennials (1976)
H. Schmidt
Abstract: A total of 3200 interspecific hybrids within and between the 2 cherry sections Eucerasus (E) and Pseudocerasus (P) were screened for their length of juvenile period.
    The E x E hybrids were the latest to flower, with P. avium and P. cerasus inheriting a longer juvenile period than P. fruticosa and P. canescens.
    The P x P hybrids start to flower one year from seed with a JP50 of 1.55 years for the group. The shortest juvenile period is inherited by P. incisa 31, P. nipponica 17, and P. concinna, the longest by P. x hillieri. The E x P and P x E hybrids show a strong maternal inheritance of the length of the juvenile period. Whereas the course of flowering in the P x E group is nearly identical with the P x P hybrids, the E x P hybrids show a slight acceleration of flowering compared with the E x E group.
     Adverse growing conditions in 1969 did not prevent P x P hybrids from flowering after 1 year, but prolonged the juvenile period in the E x E and E x P groups.