Orchids

by James O'Brien

A new interest has been added to Orchid culture by the pursuit of hybridising and raising seedling Orchids, which commenced with Calanthe Dominyi, raised in the nurseries of Messrs. Veitch and recorded in the Gardeners' Chronicle in 1858. The practice has now become general, and a large number of Orchidists arrange for the production of new Orchids from seeds, while even in small collections some attention is given to the matter. When the engrossing pursuit is first taken up, the operator should neglect no opportunity to make himself conversant with the structure of the flowers. This may be done effectually by carefully examining any available flowers, and by making longitudinal sections of the bloom by cutting them in two, commencing at the apex of the column and finishing at the ovary and pedicel. This operation exposes the various organs that are concerned in the fertilisation of the flower.

In most Orchids, such for instance as Lælias and Cattleyas, it will be seen that the pollen masses are situated at the apex of the column covered by the anther cap, the stigma being in a cavity in the face of the column beneath it.

In Cypripedium there are two developed anthers; the viscous pollen masses are not enclosed in cases, but are placed opposite each other; the stigma is a shield-shaped body seen inside the lip on the under side of the column, and the stigmatic surface is not viscous.

The details of the structure of the flowers being fully understood, it will readily be seen that the first process in the production of seeds is to fertilise the flower intended to bear the seed capsule with the pollen of the other parent selected. This is readily accomplished by lifting the pollen masses beneath the anther-cap with a thin pencil or sharpened stick and placing them on the stigmatic surface of the seed-bearing parent.

Flowers which are intended to be fertilised for seed-bearing should have their own pollen carefully removed before the pollen taken from the other plant is introduced, the pollen removed being used to effect the reverse cross, or to fertilise another species if desired.

In fertilising small flowers with the pollen of larger species, as in the case of Sophronitis grandiflora with the pollinia of the larger species, the pollen masses may be cut and a portion of it used in crossing the smaller flower. When the flower of a plant has been fertilised, the plant should receive special attention; if it is a Cattleya, Lælia, or one of the large-growing epiphytes, it should, after the pseudo-bulb bearing the flower has had a number attached to it corresponding to the number in the stock-book in which the crosses are recorded, be suspended from the roof in a comfortable and not draughty situation. If the plant is in a pot, the pot should be placed in a basket and suspended; or if a suitable position can be found on the stage, it could be placed on an inverted pot to bring it into prominence and secure for it careful attention. Where there is a number of seed-bearing plants, they should be arranged together in the respective houses in which they are grown.

Early in its development, the seed capsule should be supported by ties, which, however, should not bring it into an unnatural position, or press tightly on the part supported. From this time failure may arise from the conflicting natures of the agents used, or from various causes. Even the production of a fine and seemingly mature fruit is not a certain indication of good seeds, for seed capsules have been produced by irritation of the stigmatic surface by grit or dust, but no fertile seeds can be thus produced. On approaching maturity, a tie should be made round the middle of the capsule to prevent loss of seed when the splitting of the capsule takes place, and, when it is thoroughly mature, it should be removed, placed in a flower-pot lined with tissue-paper, and put on a shelf in a dry potting-shed until so thoroughly ripe that the seeds are being shed in the tissue-paper covering.

At this stage it is possible for the first time to determine whether the seed, or any of it, is good or not. Examination with a strong lens will show whether the minute seeds are good or not by the presence or absence of the embryo in the centre of the elongated covering, which in imperfectly developed specimens is chaff-like and not thickened in the middle as are good seeds. Where no good seeds are found, it is the custom of some growers to discard it at once, and where but few good seeds appear, attempts are made to discard the chaff and to retain the supposed good ones for sowing. Where space admits, however, especially with the beginner, it would be more prudent to sow a portion of the contents of the capsule, whether supposed to be good or not.

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.