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THE ORCHID REVIEW.
Vol. XV1.1 MARCH, 1908. [No. 183.
The question of hybridising with stored pollen, which is raised by Dr. Otto N. Witt, at page 35, is certainly interesting, and I hope that his suggestion that those hybridists who have made experiments will give us the benefit of their experience will bear fruit. I can quite understand that pollen which has been kept until dried up would be useless, and even if not dried up its vitality might be impaired by keeping, but I do not quite see why if it retained its vitality sufficiently to produce pollen tubes, and fertilise the ovules, that the resulting plants should be unhealthy. If the pollen, after storage, is able to progress to this stage all doubt about its vitality should be at an end.
I know that experiments have been made, for some years ago one of our hybridists showed me quite a sheaf of quills, in a drawer of his study, each containing pollen, sealed up, and with a small label attached, and with these he hoped to make several, as he thought, very important crosses. I met him some months afterwards and enquired how the matter was progressing. He shook his head. "No good," he remarked, "the pollen all dries up, and you might as well put little bits of stick on the stigma." I conclude that that was the end of the matter, so far as he was concerned, but I think it can scarcely be as hopeless as that. If one could only lengthen the period of the pollen's vitality by a few weeks, it might be possible to effect certain crosses which would otherwise be difficult. I had just read an article on retarding Lily of the Valley, when I came across Dr. Witt's article, and tried to connect the two together. I should not recommend freezing Orchid pollen, which I fancy would settle its vitality once and for all, but it might be possible to lengthen its life by cutting the flowers as soon as they open, and placing them in a cool cellar, changing the water occasionally. Pollen in sealed tubes or in paper might also keep better in such a place than in an ordinary room. Hitherto most of this kind of work has been done by getting the pollen parents to produce occasional flowers out of season, but there may be something in the other method.
The account of the behaviour of Paphiopedilum pollen is very interesting, and I do not remember anything quite like it before, though its consistency and the dry nature of the stigma were well known—in fact a hybridist of my acquaintance tried to hybridise one with Cattleya pollen, and as it would not adhere to the stigma he was ingenious enough to borrow some of the viscus from the Cattleya for the purpose. I rather think, however, that the
cross was not successful.
There are numerous unsolved problems among Orchids, and the figure of Chondropetalum Fletcheri given at page 56 illustrates one of them. I don't think anyone could call the plant Zygopetalum Mackayi, pure and simple—certainly not as regards colour—but on glancing at the figure of the pollen parent on the opposite page one can only wonder what has happened. The concluding phrase, " a mystery," is certainly applicable.
I have, however, an idea on the subject. The Zygopetalum character appears to have been "dominant," and the Chondropetalum "recessive," so the thing will now be to fertilise the hybrid with its own pollen, so as to extract the recessives, a la, Mendel. There are several very marked characters about the Chondrorhyncha parent, and some of them certainly ought to return if self-fertilised seedlings could be obtained. Once upon a time I should have recommended that the hybrid be again crossed with Chondrorhyncha pollen, but now let us have an experiment on strict Mendelian lines, and give the Chondrorhyncha " unit characters " a chance.
(Concluded from page 27.)
The deciduous species of the genus Dendrobium, with the numerous hybrids derived from them, furnish a group of highly decorative garden plants. First and foremost among them should be mentioned the beautiful D. nobile, which has been a very popular garden plant ever since its original introduction in 1837. It presents a remarkable series of varieties, from the pure white virginale, to the large and richly-coloured nobilius, which has been known ever since 1878, but still ranks as one of the best, though among the large importations made during the last ten or twelve years are some which rival it in size and richness of colouring. Then there are the varieties Ballianum and murrhiniacum, in which the usual dark maroon blotch is replaced by one of a light rosy shade, Cooksonianum, in which a disc-like blotch appears on the petals, and burfordiense, in which similar blotches occur at the base of the lateral sepals. An account of the principal varieties was given at pp. 147-150 of our third volume.
D. Nobile is very easily grown into large specimen plants, and one such is shown in the annexed illustration (fig. 10), which was grown in the collection of Mrs. G. Knowles, Hollin Hall, near Bradford, by Mr. Moorby. It is a noble specimen, grown in a 14-inch basket, and bears over 1,100 flowers. The longest stems measure 4* feet high, and a noticeable feature of this plant is that the foliage of the previous year's growth is well preserved,
which greatly enhances the appearance of the specimen. This is attributed to the method of treatment, no severe rest being given. When the growths are mature water is gradually withheld, but the stems are never allowed to shrivel. The plant was grown with others in a house devoted chiefly to tomatoes, and was top-dressed annually with fresh peat and sphagnum. Five years before it was a starved specimen in an eight-inch pot, with stems ten inches high. It is a very fine example of good culture. The species is very accommodating, and is often grown remarkably well in an ordinary stove or cucumber house, and rested in a vinery. It is invaluable for cutting, and lasts a long time in water if the stems can be cut with the flowers attached.
D. Benson.e (fig. 11) is another very handsome species, having creamy white flowers with a yellow disc to the lip, on which usually occur two maroon eye-like blotches. It is a dwarfer plant than the preceding, and equally floriferous, though it often has the reputation of being difficult to grow, which is evidently the result of unsuitable treatment, for Mr. James Cypher once remarked :—" I have grown it for eight years, and at the end
Fig. i1. Dendrobium Benson.e.
of that period had finer bulbs than those imported. I believe that many, or nearly all, are lost by having too much water during winter or early spring, and even when the new growths are several inches high they should receive very little water." It is particularly liable to the attacks of red spider, which, however, can be kept in check by sponging with the usual insecticides. It is a Burmese species, and was originally discovered by Colonel Benson, and introduced by Messrs. James Veitch & Sons in 1866. The locality was given as mountains nearTongou, west of Prome, at an altitude of about 1,500 feet, whence it extends southwards as far as the latitude of Moulmein. The late Major-General Berkeley stated that the form found in the Kareen hills, not far from Shoaghyn, is immensely superior to the Arracan form. The plant figured was grown in the collection of the late R. I. Measures, Esq. D. Bensonae has been successfully hybridised with D. nobile, D. moniliforme, D. Maccarthiae, and D. X Cassiope, giving a group of very pretty little hybrids.
D. Atroviolaceum (fig. 12) is a plant of a totally different type. It is one of a group of several species found in New Guinea and the adjacent islands, of which the mossy-pedicelled D. macrophyllum is one of the earliest and best known. The leaves are usually two or three in number, and occur at the summit of the stem, from which point the inflorescence is
Fig. 12. Dendrobium Atroviolaceum.
produced. D. atroviolaceum was introduced by Messrs. James Veitch & Sons, and flowered for the first time in Europe in 1890. It is easily distinguished from D. macrophyllum by the absence of pubescence from the pedicels. The sepals and petals are cream yellow, with numerous dusky brown spots, and the strongly three-lobed lip is deep violet purple, with some dull green markings outside. The flowers have a peculiar pendulous character, so that the richly-coloured lip is best seen from underneath, The New Guinea species should not be rested in a cool temperature, like