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The Waterlilies A Monograph of the Genus Nymphaea Henry S. Conard The Carnegie Institution of Washington, 1905 CHAPTER VII. HYBRIDS AND GARDEN VARIETIES.

Beginning with Nymphaea devoniensis in 1851, a continually increasing number of forms of waterlily has become known to cultivators. The origin of these was in some cases accidental, in others due to artificial hybridization. In the first case there may have been cross-pollination by insects, or variation or mutation -- all equally problematical to the systematist and uncertain for the general student. In the second case, careless or ignorant methods leave room for much doubt as to parentage, and very often the facts are withheld or distorted for trade purposes. Only in very few cases, therefore, is our knowledge of the origin of the various garden varieties at all reliable or useful.

For example, N. devoniensis, which appears on plate 4665 of the Botanical Magazine, and was first described by Paxton in Gardeners' Chronicle for July 10, 1852, is said in the former article to have been produced by crossing N. rubra with N. lotus -- a red species with a white. The seeds were obtained in autumn of 1850 at Chatsworth, England, and the plant is said to have flowered from April to October, 1851. But the points of difference of the so-called hybrid from N. rubra are more robust growth, more floriferous habit, and a very slightly lighter color. In other words, there is almost no trace of the influence of N. lotus. Since Hooker and Thomson stated that just such a plant is common and native in India, its hybrid origin is generally disbelieved. It is probably a self-fertilized seedling of N. rubra. As to the color of leaves and flowers, we had in the summer of 1901 three flowering plants of N. rubra (?) raised from one and the same tuber. One was grown in a half-barrel of earth in a tank 1.4 meters square, in company with N. marliacea-chromatella, N. tetragona, and the water-poppy; the flower was of a light magenta red, and the leaves brownish green. Another was in a half-barrel in a pond with plenty of leaf-room, and had deep red-brown leaves and pure magenta flowers. The third was in a tub of earth 1.6 meters in diameter and 60 cm. deep, with plenty of leaf-room; it resembled the second, but had larger leaves and flowers, and the latter still deeper in color. There is, therefore, great variation, according to conditions of growth.

On the other hand, N. ortgiesiano-rubra, exhibited at Chiswick in May, 1852, by M. van Houtte, and described by Planchon (1852 aa), is in many respects intermediate between the two parent types. The seed was obtained in the summer of 1850 by M. Ortgies in Van Houtte's aquaria, by removing the stamens from a flower of N. rubra and dusting the stigma with pollen of "N. ortgiesiana." The comparison of hybrid and parents is well shown in Planchon's parallel column descriptions. The hybrid has bright rose-pink flowers, but they open wide as in N. ortgiesiana. The styles are yellow, washed with red in N. ortgiesiana, reddish orange in the hybrid, dark brownish red in N. rubra. The color of the stamens and upper surface of the leaves is fairly intermediate, but the under surface of the leaf and the character of the stigma are as in N. rubra. The robust temperament of N. ortgiesiana is reproduced in the hybrid, but it is more floriferous than either parent, probably because no strength is used up in the production of seed. In short, N. ortgiesiano-rubra is a well-marked hybrid. Several other hybridizations are recorded by Planchon (1. c.) as productive of seed in 1852, but no further results reached the public.

In 1853 M. Bouché, Inspector of the Royal Botanic Garden of Berlin, obtained another hybrid, named by Planchon (1854) N. boucheana. It is to all appearance intermediate between N. lotus and N. ortgiesiano-rubra, but is of the same parentage as the latter. A slightly different form of N. lotus, viz., N. dentata, was used as pollen parent. The pale pink petals bordered with pure pink, the yellow stamens, and the bright green leaves show a preponderating influence of N. lotus. The sterility of N. boucheana attests its hybrid origin.

N. kewensis was next to appear. It was published in Gardeners' Chronicle in 1887 (p. 366), and in Botanical Magazine in April, 1888 (tab. 6988). The cross was made at Kew in 1885 by Mr. Watson, with N. lotus as seed parent and pollen of N. devoniensis. The hybrid has a large number of broad petals of an even rosy pink all over; the stamens are orange colored; the leaves are pure dark green above. In recent years, crossing and re-crossing has been carried on in this group, especially in America, until every shade of color may be had between the white and red types; differences are also noted in shape of petal, size of flower, and color of leaf. They are propagated readily and quite accurately from the tubers, and names have been given to every distinguishable form. N. ortgiesiano-rubra and boucheana are not found under those names, but very similar plants are cultivated. The name kewensis is still retained, though the original plant "died without issue"; the present stock was obtained independently in America. Hybrids of the Lotos group are known in Germany under an entirely distinct set of names from those used in this country.

In 1885-1890 M. Latour-Marliac, of Temple-sur-Lot, France, drew the attention of flower-lovers everywhere by his magnificent hybrids in the Castalia group -- the hardy waterlilies. Probably no one else has done so much for waterlily culture. His earliest achievements won universal admiration; but these have been followed by annual additions of ever increasing splendor. At present, however, the possibilities in that direction seem to be about exhausted. So great was Marliac's lead in this work, and so carefully did he guard the secret of his success, for trade reasons, that only within the last three years have any comparable results been attained, and this only by using Marliac stock for breeding. The parentage of the Marliac hybrids is a matter of speculation. In several cases, however, one or both parents can be indicated with considerable certainty; but which was male and which female will, I fear, never be known. The first members of this series were the yellows, N. marliacea-chromatella, N. odorata sulfurea and N. tetragona helvola. All are derived from N. mexicana. They are altogether sterile. Of some of the pinks N. odorata rosea is one parent, and of those with red tints at the center of the flower N. alba rubra is one source.

Within the Brachyceras group, hybridization has been carried on almost exclusively in America. Here Mr. Tricker is the acknowledged leader, so far as the public good is concerned. His N. pulcherrima, derived on one side from N. caerulea, has been for several years in general cultivation. The new hybrids of N. flavo-virens with pollen of N. zanzibariensis sent out under the rather unwieldy names Mrs. C W. Ward and Wm. Stone, are easily the finest tender day-blooming hybrids yet available. Both have the general habit of N. flavo-virens, and in the tuber they follow this parent exactly; but the color of the flower and leaf is beautifully intermediate. N. pennsylvania and N. elegans X zanzibarziensis, raised in 1901 at the University of Pennsylvania Botanic Garden from seeds of the previous summer, are fairly intermediate in forms, coloring of all parts, and number of floral organs between their respective parents.

In spite of many attempts, no cross has yet succeeded between members of different subgenera of Nymphaea as grouped in this paper. We realize that this is in opposition to M. Marliac's published statements in which he claims N. rubra as the source of the red color in his hardy red waterlilies. But so far as naked-eye examination goes (and we acknowledge that is weak argument) the kind of color shown by the hybrids is totally different from that of N. rubra, and no trace of the latter species is to be found in any part of the plant. We are also forced to take issue concerning the supposed hybrids between Lotos and Hydrocallis* raised by Mr. Ames at North Easton, Mass. (Ames, 1900; Grey, 1900). I have the greatest confidence in the accuracy of Mr. Ames, and of his able gardener, Mr. Grey, and the latter assures me that the seed-flowers were carefully castrated and kept netted from insects. But the so-called hybrids show absolutely no trace of the influence of a Hydrocallis parent, and it is easier to believe that parthenogenesis or asexual budding from the endosperm or perisperm has occurred in the highly fertile N. lotus flower than to imagine a hybrid parentage with one parent obliterated. The case demands, and might well repay, a rigid investigation. Similar crosses of distantly related species have been repeatedly claimed, and by such authorities as Planchon, Tricker, and Sturtevant, but they have either failed to reach the public or have shown no trace of the pollen parent; sometimes, indeed, there is strong evidence of the pollen of some related species.

Natural hybrids, i.e., those produced without human intervention, are of frequent occurrence whenever kindred species are in the same pond. Caspary and others have recorded hybrids of N. alba and candida from Europe, and intermediate forms between N. odorata rosea and N. tuberosa spring up in our gardens; N. odorata caroliniana and N. o. luciana are of such origin. N. flavo-virens always becomes mixed with N. zanzibariensis if the two are near each other.

From the fragmentary nature of our knowledge it is impossible to draw any general conclusions on the laws of heredity in waterlilies. So far as we can see, some characteristics are regularly blended in the hybrid offspring, while others are carried over in toto, or even exaggerated, from one or other parent. Thus, the spotting of the calyx so characteristic of N. caerulea is not a whit diminished in N. pulcherrima and N. pennsy1vania, while in both the color of petal and size, shape and number of all of the floral parts are decidedly intermediate. In N. Wm Stone, as stated above, the caudex is exactly like that of the seed parent, N. flavo-virens, in size, shape, character of leaf-bases, hardiness, and keeping qualities. In Brachyceras all known hybrids are sterile, except N. capensis X zanzibariensis raised in our botanic garden, which is highly fertile, and of which a new generation of hybrids is coining on. All of the hardy yellow hybrids are entirely sterile, and crosses of N. tetragona with Eucastalia types are also sterile; as examples of these N. laydekeri-rosea and N. pygmaea alba Marliac may be mentioned. Even N. alba X candida is greatly enfeebled in seed-producing capacity. But N. alba and N. a. rubra, though much more distinct than the last two to the casual observer, are perfectly fertile together and have fertile progeny. N. odorata and tuberosa hybrids are not self-fertile, but can be crossed with pure species. In the Lotos group, some forms are sterile, others fertile. Planchon found N. ortgiesiano-rubra to be impotent as to the ovules, but capable of fertilizing N. lotus or N. rubra. In those now in cultivation, N. devoniensis is nearly sterile, but N. omarana, which closely resembles N. origiesiano-rubra, often produces seed. In general, the nearer the hybrid approaches in color to the highly fertile N. lotus, the more productive it is. Several seedlings of N. omarana have been raised, of which N. Geo. Huster deserves special mention. Its flowers are of an extremely deep dark red, more so than N. rubra itself, as cultivated here. If the original seed was fertilized by pollen of the same flower, which it is impossible to know, we would have a case of "separation of characters" according to Mendel's theory ; but even if N. rubra was the pollen parent, the determining elements of the color of the flower in this seedling seem to have lost all trace of the influence of a white ancestor.

We have expressed a belief in the occurrence of variations under cultivation without mixture of blood. Probably N. odorata exquisita is such a variant from N. odorata rosea, as also N. froebelii from N. alba rubra, N. devoniensis from N. rubra, and N. gladstoniana from N. alba; N. gladstoniana is quite fertile, and has seeds and arils like N. alba. Whether N. alba candidissima belongs in this class or among the hybrids is uncertain. It is absolutely sterile, and may be a cross of N. candida with the large N. alba of Greece. Quite comparable with these varietal changes in natural forms are some suddenly appearing peculiarities of hybrids. For example, N. robinsoni can be easily recognized by a peculiar crimped notch and fold about the middle of each side of the sinus of the leaf; N. gloriosa is uniformly pentamerous; and one of a set of plants of N. Gladstoniana X mexicana raised by Mr. Tricker habitually twists the petiole so as to turn the apex of the leaf instead of the sinus toward the center of the plant. N. ladekeri rosea prolifera is a fasciated strain, which stools out around the crown to a remarkable degree, whereas the type makes no lateral buds at all.

Without going farther into isolated details, enough has been said to show that a wide and interesting field lies open to the student in crossing and inverse crossing of waterlilies. It is unfortunate that Caspary's extensive investigations in this line have not been formulated, but his notes, exquisite color sketches, and large collection of pressed specimens are preserved in the Royal Herbarium of Berlin. Among them are such crosses as N. capensis X caerulea; N. capensis X (capensis X caerulea); N. caerulea X [caerulea X (capensis X caerulea)]; N. caerulea X {caerulea X [caerulea X (capensis X caerulea)]}; N. flavo-virens X [capensis X (caerulea X micrantha)].

Duplicate specimens of many of these hybrids were distributed to several other herbaria. Time did not permit us to make a study of these. We hope they will be worked over by some scholar, and the interesting results made known. We have, for the convenience of students and cultivators, brought together, in the following pages, some account of the hybrids and garden varieties that have come more directly under our notice.

* Mr. Ames' N. ampla, which I saw in 1901, is N. rudgeana Mey., collected by Mr. Grey in Cuba. The so-called crosses may be "false-hybrids."