Orchids Part 6

SEED SOWING

A number of the seeds of all seed capsules should be sown as soon as they are ready, the remainder being carefully stored for sowing later if required, the seeds sown and those retained being carefully marked with the number in the record book.

The manner of sowing the seeds varies in different establishments, satisfactory results having been obtained under very dissimilar conditions. Failure at first is the usual record of the amateur taking up Orchid hybridisation, although some few get fairly good success from the commencement, while those who have had a run of bad luck usually conquer in the end if they persevere. A scientific reason for some failures has been given, namely, that an endophytic fungus said to be necessary to the development of the freshly germinated seeds is wanting in the early stages, but may be developed naturally after a time, and a better state of growth result. Be that as it may, it is a curious fact that the line of demarcation between failure and success in the matter of raising seedling Orchids is very narrow, and, when the operator succeeds in raising a fair proportion of the seeds sown, he is generally surprised at his former want of success, apparently under practically similar conditions. Formerly the common practice was to sow the seeds on the surface of the material in which the parent plant was growing, or a plant of some kindred variety. This practice has been generally satisfactory and continues in most amateur collections to the present day. A plant in a basket, or suspended pan or pot, is best, the subject being chosen for the good quality of the peat, Osmunda fibre, or whatever material the plant may be growing in. The Sphagnum-moss on the surface should be clipped very short, the plant thoroughly watered with rain water, and allowed to drain for a few hours. The seeds should be sown a few at a time, on the point of a knife or thin strip of hard wood or ivory, and carefully and evenly distributed over the surface of the material in which the selected plant is growing. In all cases the number of the record in the stock-book should be attached, a small celluloid tablet fastened by a thin wire being the best label, as it is clean and durable. Hybrids of Laelia, Cattleya, and other true epiphytes should be suspended in a warm, intermediate house, and Cypripediums and terrestrial Orchids may be sown in a similar manner in the pots of either the seed-bearing subject or similar kinds and placed in a moist, sheltered corner of a house, in which a genial warmth is maintained, the plants being elevated on inverted flower-pots. Once the seeds are sown, the plants fostering them should never be allowed to get dry.

Odontoglossum seeds come up best when sown on the surface of established plants in the manner described. To ensure the best results two or three sowings of each should be made, and the plants bearing the freshly sown seeds placed in different parts of the house, some being suspended and others placed on the stage.

The maintenance of a continual and even amount of moisture after sowing, and until the seedling plants send forth roots, is of the highest importance. To water either with a spouted or a rose pot overhead would wash the seeds away. To avoid this, some resort to the practice of dipping the plants on which the seeds are sown, allowing the water to reach only to within an inch of the surface of the compost. This is better than watering overhead. Spraying with rain-water is an excellent means of securing uniform moisture, although it requires more care and attention than dipping. The sprayer is a great help in all stages of seedling Orchid growth, not only as a means of conveying moisture direct, but by spraying around the plants and on the staging it is a great aid to maintaining a moist atmosphere. Let the moisture be conveyed in whatever manner it may, it must not be forgotten that the seeds will perish soon after germination if allowed to get quite dry, either from failure of moisture in the material on which they are sown, or from an excessively dry air surrounding them. Against the above-mentioned practice of sowing the seeds on established plants, it is urged that in that way there is no certain means of keeping the different crosses from being mixed, by reason of the seeds of one kind getting into the water-tank and being thus conveyed and mixed with others; and by seeds falling from plants suspended overhead and coming up on plants beneath, and in other unexpected places. Such acquisitions, though often very acceptable, are puzzling, as there is no record of their origin, or if they come up amongst seeds which have a record, the chance introductions sometimes have a wrong parentage a.s.signed to them.

[Ill.u.s.tration: PLATE VI

CYMBIDIUM LOWIO-EBURNEUM

(This plant has been commended for its culture on two separate occasions by the R.H.S.)]

To lessen such risks, it is the custom of some growers to arrange a seed-raising case, constructed like an ordinary propagating case, in form like a miniature lean-to, or span-roofed Orchid house. This is arranged over a part of the staging where there is a slight warmth from the hot-water pipes. The staging has a few inches of cocoa-nut fibre, or chopped Osmunda fibre, fine ballast, or other moisture-holding substance, and on this a number of inverted flower-pots are closely arranged to form stands for the pots or pans in which the material for sowing the seeds on is placed: or a light, open wood-work staging is arranged. The favourite surface for sowing the seeds on is prepared by stretching a small square of coa.r.s.e calico or fine light muslin shading material over a ball of Sphagnum-moss, and pressing it into a 60 or small 48 size flower-pot, so that the unwrinkled convex surface of the ball has the centre just below the level of the rim of the pots, the sides being lower. These are thoroughly soaked and allowed to drain before sowing the seeds on them, and they are then placed on the inverted pots in the case. The covering of the case is sometimes of the nature of hinged sashes to lift from the front, but the most convenient and best covering is that formed of sheets or panes of gla.s.s cut about one foot wide and of a length sufficient to cover the frame, by resting one end on a groove in the front side of the case, and the other on the top bar. A sufficient number of these sheets of gla.s.s should be provided to cover the frame; they are excellent, as they give a certain means of continual ventilation in some degree through the laps of the gla.s.s, even when closed, and they may be closely or openly arranged to regulate the amount of air admitted. Such pieces of gla.s.s can easily be removed to inspect the seedlings.

What is commonly called "coddling" causes great mortality among Orchids, and in this particular the use of seedling cases, if not very carefully and sensibly worked is less likely to be satisfactory than sowing the seeds on plants growing in the houses. Too much heat is very harmful.

Odontoglossums proved difficult to raise at first, and this was mainly because the seedlings were kept too warm and close. If the cultures are carried on in the Odontoglossum house, success is generally attained, although the products are seldom so numerous as in Cattleya, Laelia, and Cypripedium hybrids.

Another plan adopted by some growers, and with tolerable success, is to place squares of Osmunda fibre in pans, and after soaking them, sow the seed on them. Others have discs of soft wood, such as Willow, cut across the grain and placed in flower-pots or pans with the fibre of the wood-grain uppermost; after soaking the discs, the seeds are sown on them. When not raised in gla.s.s cases, round or square pieces of gla.s.s are placed on the pots. Indeed, there is ample evidence that, provided good seeds are sown and placed in a suitable temperature, Orchid seeds germinate readily. The first sign of vitality is given by the good seeds a.s.suming a green appearance; in time they become little spherical green bodies, which later produce a growing point; in due course the true root appears, and the little plants are ready for p.r.i.c.king off or transplanting into previously prepared store pots prepared with a good drainage of small crocks or broken charcoal in the bottom, some Osmunda fibre or other Orchid potting material, and an inch or so of very fine compost formed of decayed leaves, Osmunda fibre, or good Orchid peat and Sphagnum-moss in equal parts, the whole rubbed together through a fine sieve. Some add a proportion of sand to this compost. The whole should be thoroughly well watered before the tiny seedlings are placed a quarter of an inch or so apart in small holes in the surface of the compost and sprayed to settle them in position. Up to this stage the greatest mortality is observed. Wide crosses between species of dissimilar nature, and which have up to the production of the growth point or root appeared to be doing well, having shown that they did not belong to the unfertile, suddenly collapse. Those which have taken a long time to germinate have fallen victims to the minute fungi, and other low forms of vegetable organism, which, commencing at one or two spots, have gradually overgrown the surface of the pot and destroyed them. The stronger are often destroyed by small insects, while drip, however carefully guarded against, claims its share of the spoil. These things are specially vexing to the amateur who is working in a small way. To the expert cultivator who has a mult.i.tude of subjects in hand, and whose methods and appliances mitigate the evils, the losses are not so serious, for when Orchid seeds germinate freely they provide for losses when sown on a large scale. Nothing is gained by removing the little seedlings from the seed pot or basket too early. If thriving, they should be left until they are large enough to be handled safely.

But where there is overcrowding, or "damping off," or decay from fungus, it is best to remove some or all of the little seedlings in any stage of growth to the store-pots.

The store-pots should be returned to the seedling case, or placed on a shelf near the gla.s.s in a warm, moist house, where the seedlings should increase in size until they are ready to remove to fresh store-pots, when they may be given more room; or if large enough, they may be placed singly in thimble pots, or three or four seedlings may be placed round the rims of thumb pots.

Seedling Odontoglossums, when large enough to occupy thimble pots, are found to thrive well when the pots are fixed in pans or shallow seed-boxes in Sphagnum-moss, and placed on a shelf near the gla.s.s in the Odontoglossum house, where, like other seedling Orchids, they should be lightly sprayed several times each day in fine, warm weather, and as often as may be deemed necessary in colder and dull weather.

From the time the little plants are established in small pots until their flowering stage, it is only a matter of ordinary culture, although, as a rule, the small seedlings are safer with four or five degrees more heat than is afforded the established plants. In the matter of growth from the seedling stage to the flowering plant, there is but little need of a resting season, even with species such as are deciduous when mature, although a diminished supply of water may be given for a short time to any which, having completed a growth, show no sign of developing a fresh one. In most cases, a thorough drying, even if it does not destroy a seedling, causes the flowering season to be delayed by a year, or even longer.

The careful shading of the seedling house is a very important matter.

Very young plants do best in a subdued light, and until they are quite strong plants they should not be exposed to direct sunlight. A hot summer often kills even the plants which have been brought satisfactorily through a long winter. It is, therefore, advisable to have on the seedling house, in addition to the lath roller blind, running on supports carrying it well above the gla.s.s of the roof, either a second lath roller blind running an inch or so above the gla.s.s and beneath the upper one, or a permanent thin cotton shading, which may be tacked on in spring and left until autumn; or, preferably, so fitted that it can be rolled up when it is not required.

SELECTION OF SUBJECTS FOR HYBRIDISING

The best varieties procurable should always be selected for hybridising, it having been proved that crosses originally made with indifferent varieties are much finer when raised again from more carefully selected varieties.

There seems to be no certain limit to the possibility of crossing; even the most dissimilar genera may be crossed with some probability of getting a successful result.

POTTING MATERIAL FOR HYBRID ORCHIDS

From the time the little plants are well established in single pots, the same potting material used for all of their kind may be employed, the plants in the earlier stage having the potting material in a finer condition than that provided for the larger plants as they approach the flowering stage.

As with other important operations, in Orchid potting and in the material used the practice varies considerably, even in the best collections, and this points to the fact that if the accommodation is good, the houses properly heated, and other details of culture carefully carried out, the exact composition of the potting material is of minor importance. For Cattleya and Laelia hybrids and a large number of epiphytes grown with them the compost is made by tearing up the materials with the hand, or in some other way which will not break the fibres very much. Osmunda fibre forms one-half to two-thirds of the compost, the other third being made up of good Sphagnum-moss and Oak leaves or other decayed, dryish leaves. We do not recommend leaf-soil or leaf-mould, which was formerly strongly advocated, especially by Continental growers, who used it with disastrous results. The most that is done now is to mix a proportion of it with other potting material for Lycastes, Calanthes, Phaius, and similar strong-growing terrestrial Orchids.

For mixing with the compost for hybrid Orchids, some use crushed crocks, sand, charcoal, and a small proportion of each or either may be employed safely, although there is no real need for such materials.

Polypodium fibre may also be subst.i.tuted for Osmunda fibre, or a proportion of each may be used. Orchid peat fibre, which used to be the chief potting material for Orchids, is still perhaps as good as any of the other fibres, provided a really good quality can be obtained, a matter which has become increasingly difficult.

For Cypripediums, and especially Selenipediums, a proportion of good, fibrous loam should be added to the compost recommended for epiphytal Orchids, the proportion of loam being increased as the plants get larger. Phaius, Calanthes, Zygopetalums, Zygocolax, and other plants of a similar character should also have a proportion of loam-fibre in the compost, and in these cases Orchid peat may be subst.i.tuted for Osmunda fibre, if it is of good quality. So far as it has been tested, Osmunda fibre has an advantage over other fibres, in that it is more durable, retaining its fibre intact longer than any other. Osmunda fibre and Polypodium fibre in equal proportions, with an addition of leaves and Sphagnum-moss, make an excellent material for all young, epiphytal Orchids, the finer Polypodium fibre, if well worked in, giving substance to the more open Osmunda fibre.

For very small plants it is well to rub the mixture through a coa.r.s.e sieve, but after the early stages the use of the sieve should be discontinued, and the compost carefully mixed with the hands.

CHAPTER XX

ENUMERATION OF THE PRINc.i.p.aL GENERA AND SPECIES IN CULTIVATION

~Acanthophippium.~--A small genus of terrestrial plants with oblong pseudo-bulbs, and broad, plicate leaves. Scape erect, flowers ventricose, yellow and reddish-purple. Warm house. Pot in equal parts of turfy loam, peat, and leaves. Rest dry after the leaves fade and growth is completed. The most familiar species are _A. bicolor_, _A.

javanic.u.m_, and _A. striatum_.

~Acineta.~--The species of Acineta are epiphytal Orchids with stout pseudo-bulbs and broad, coriaceous leaves. The flowers are produced in pendulous racemes; they are fleshy, whitish, or yellow, and spotted with purple or brown. They should be grown in baskets suspended in the intermediate house. _A. Barkeri_, _A. densa_, and _A. Humboldtii_ are free-growing species.

~Acropera.~ _See_ ~Gongora~.

~Ada.~--Cool-house genus from Colombia. Leafy evergreen plants with racemes of orange-scarlet flowers. _Ada aurantiaca_ is almost the sole representative of the genus in gardens, and should be grown even in the smallest collections.

~Aeranthus.~ _See_ ~Angraec.u.m~.

~Aerides.~--A large genus of evergreen Orchids with distichously arranged, leathery, green leaves, the stem producing air-roots freely. Natives of India, the Malay Archipelago, and other parts of that region, extending to j.a.pan.

All the species of Aerides may be grown in pots, crocked from one-half to two-thirds of the way up, the old stems of the plants, when long, being placed in the pots before the crocks are filled in. The surface should be of good living Sphagnum-moss, and the plants should be liberally watered from the end of February or beginning of March until autumn, when the supply of water should be restricted according to the condition of growth of the plants. Those which have finished their growth and are not showing new leaves in the centre should be given the least supply, but it is not advisable to dry any off completely, unless for some reason they have to be kept comparatively cool throughout the winter, when they are safest if kept tolerably dry. The smaller species may be grown in baskets with advantage when convenient--indeed, the true epiphytal character of the whole genus would suggest that method as the better, but experience has proved that they may be equally well grown in pots. The warm house, or warm end of the intermediate house, suits all the species, but _A. j.a.ponic.u.m_ may be grown in the cool house. Most of the species have white and rose-coloured flowers, and they are very fragrant.

_A. odoratum_, one of the oldest of garden Orchids, is one of the best and most free-growing species. _A. crispum_, _A. cra.s.sifolium_, _A.

Fieldingii_, _A. Houlletianum_, _A. falcatum_, _A. Lawrenciae_, _A.

multiflorum_ in its many forms, _A. quinquevulnera_, _A. suavissimum_, and _A. virens_ are the best for amateurs.

_A. cylindric.u.m_ and _A. Vandarum_ have terete leaves like _Vanda teres_, the former with white flowers, having a fleshy yellow and red lip, and the latter, which is more membraneous in substance, being white. Although often confused with each other in gardens, there is little resemblance between these two species.

~Aganisia.~--This genus thrives best in Orchid pans in the intermediate house, in the ordinary compost used for epiphytal Orchids, with an addition of leaves. Place the plants in a moist situation.

_A. caerulea_ is of trailing habit, and has blue and white flowers. _A.

ionoptera_ is white and purple, and _A. lepida_ white.

~Angraec.u.m.~--A large genus chiefly from Africa and Madagascar, and requiring similar treatment to Aerides. Botanists have divided the genus into Aeranthus, Listrostachys, Mystacidium, &c., but for garden purposes the one generic t.i.tle suffices. The flowers of nearly all the species are white and fragrant, many of them being furnished with long, greenish spurs.

A representative selection could be made with _A. arcuatum_, _A.

Ellisii_, _A. Humblotii_, _A. infundibulare_, _A. Kotschyi_, _A.

modestum_, _A. Scottianum_, _A. superb.u.m_ (_eburneum_), and _A.

sesquipedale_, the last-named Madagascar species being the finest of the genus.

~Anguloa.~--Colombian and Peruvian Orchids of strong growth, and similar in habit to Lycaste. The flowers are usually produced singly on upright stems. Pot in two-thirds peat and one-third Sphagnum-moss or Osmunda fibre. When good loam fibre can be obtained, a small proportion may be added. Intermediate house. Rest tolerably dry and cool after growth is completed. _A. Clowesii_, yellow; _A. Ruckeri_, yellow and dark-red; _A.

uniflora_ and its variety _eburnea_, white.