Orchid Cross Pollinating

When it comes to orchid cross pollinating, nature's schemes for perpetuation of the orchid species work with wonderful precision.

A peculiar balance seems to be observed in that rarer and less productive orchids have developed a more complicated and thus more accurate and certain method of cross-pollination.

Self-pollination is discouraged by nature. Even in the few orchids capable of it, the process seems only to be used when insects fail to appear.

The process of pollination is comparatively simple in genera with large, open flowers, having short, fairly wide, easily accessible nectaries as, for example, Cattleya, Laelia, Phaius, Sophro-nites, Bletia, Coelogyne, and Cymbidium. Bees readily perform the service.

In greenhouses with wide-open vents the bees frequently pollinate indiscriminately and many wilted flowers result.

Those having a longer nectary, like the Angraecum, are pollinated by moths. Members of the genus Vanda and perhaps of Aerides are probably cross pollinated by a larger moth.

Some of these that produce only a few flowers also manufacture extremely firm cement for attaching the pollen masses to the insect, preventing loss in flight. Certain types of Cypripediums are attractive only to small bees. Epipactus latifolia finds its needs best served by wasps.

Darwin reported that a Dr. Criiger had observed swarms of bees actually feeding on the crests of the labellum of Coryanthes, a weird flower with a hooded dorsal that appears to crouch down over the labellum.

Its most interesting characteristic is a bucket-shaped appendage peculiar to the species.

This is filled with a slow-dripping fluid, not a nectar, whose purpose seems to be to wet the wings of the hungry bee when he passes the slippery sides and thus force him to creep through a narrow passage.

Here he forcibly brushes the stigmatic cavity, finds crests spread for him to nibble, and picks up the pollen while feeding. He flies off and repeats the process on another Coryanthes and the cycle is completed.

In Pterostylus, after the insect enters, the labellum shuts a little trap door, forcing him to leave by the back through a passageway where the cramped quarters facilitate the performance of his function.

Masdevallia fenestra never fully opens but has tiny windows that remain open until pollination occurs, when they are drawn shut. Darwin admitted that he was never able to determine the method of pollination for this flower.

As amazing as are these structural oddities, they are no more so than the means by which the pollen masses adapt themselves to a position suited to their proper delivery. Rutherford Platt in This Green World has reported that the Orchis, fertilized by bees, attaches the pollen masses to the bee in erect horns, which, however, wilt down in a manner that permits them to hit exactly the waiting cavity of the next flower. If they remained erect they would not fit.

Calopogon carries its stigma on the bottom part of the petal, and when the bee lands with a pollen load he is neatly flip-flopped into a somersault that brings the pollen on his back to proper contact.

In Cypripedium acaule the bee is attracted to the entrance by white lines, pushes through the softly drawn drapes of the pouch of the 'lady's slipper,' and sips the nectar, but when he seeks to retreat, the drapes are closed tight behind him.

By squeezing through the only open place, the hole at the top, he first scrapes the pollen on to the stigma and then, pushing past the pollen masses at the top, picks up another load. Apparently undaunted he flies to another rosy slipper and repeats the routine.

In Catasetum the vital pollen is stored in a secret chamber inaccessible to the visitor and, as already described, is discharged by a miniature catapult at the intruding insect.

Most interesting of orchids, Catasetum appears to be an exclusively male form, and Momtchanthus viridis, which has only rudimentary pollen masses, the female of the same species.

The cross pollination of orchids is a subject that still has ample room for original research. Far too little is known about the subject. Are the so-called spider orchids (Cryptostylis arachnitis) fertilized by spiders, the Arachnis muscifera, resembling flies, by flies, and the bee orchids (Bee Ophrys) by bees?

Is it the putrid smell of Bulbophyllum putridum, or foetidum, that attracts, and are the attracted insects those that feed on decayed vegetable matter? Patient and close observation will be needed to discover the answers.

In addition to the great variety of inducements and ingenuity of nature to insure pollination, the orchid plant, compensating for the extreme danger threatening its very tiny and powdery seed progeny, produces this seed in great profusion.

Darwin cited an instance of one pod with approximately 6,020 fertile seeds, the plant bearing four such capsules.

When it comes to orchid cross pollinating, one plant of Orchis maculate produced thirty seed pods, each pod containing about 6,200 seeds, or a total of 186,300. Fritz Miiller found 1,756,440 seeds in a single Maxillaria pod.

The world would be overrun by orchids were it not that the seed prospers under conditions that are equally favorable to its enemies, pests and fungi.

The orchid seed's chance for survival is further reduced by the fact that it is not in itself supplied with sufficient food but must depend on outside help—a friendly fungus called Rhizoctonia, supplanted in artificial cultivation by chemical nutrient.

Another important disadvantage of the orchid seed is that, as compared to other plants, it is singularly undifferentiated into roots, leaves, and endosperm.

The matter of propagation is of utmost concern to the grower. Propagating from seed, is a rather technical method for beginning amateurs, but other methods of propagation, either natural or artificial, seem prosaic compared to the thrilling story of seed production and seed growing.

In some ways, however, they are more advantageous, in that they are simpler and produce a flower of certain appearance.

Plants of sympodial growth, that is with the new growth coming out of the base of and alongside the old bulbs, will be found to propagate readily by division. Cattleya, Laelia, and Cym-bidium are typical of this type. Cypripedium is frequently found to divide itself in nature even more readily than others of the type.

The Cattleya permits division as long as three or four bulbs are allowed. Each year in the life of the Cattleya adds a new growth at the front end of the plant, and certain species may occasionally grow in two and, more rarely, in three directions. As the new bulbs form, the old ones frequently begin to lose their leaves and roots.

They become 'poor relations,' a drag on the living plant. On being severed from the living plant the backbulbs, as these old drybulbs are called, will, if placed in a warm, moist spot, start life over. After two, three, or perhaps four years these will be new plants and will flower.

The advantage of the backbulb type of propagation over the growing of seedlings is that the flower will exactly resemble that of the original plant, while in the seedling there is no way to tell whether it will resemble one parent plant or the other or be something entirely different.

Plants of monopodial growth, like Vanda, Renanthera, and Angraecum, with the new growth appearing continuously from the top or crown, will not divide so readily. The only method of propagation for them, other than seed growing, is to cut off the top of the plant below several of the husky aerial roots.

On being potted, the top part may take root and become a new plant. It is a risky practice, however, and is not especially recommended to amateurs unless for some reason the crown of the plant has become damaged and appears dead.

When the top is cut off or injured in this fashion the bottom part will probably develop adventitious plants. This type of plant is a slow grower and needs to be very large before flowering, so that any kind of propagation is a slow and tedious process at best.

Phalaenopsis, while differing from Vanda in that it is stemless, is also of monopodial growth and not divisible. It will occasionally throw adventitious plants from the nodes of the flower stem.

Experiments have shown that it is possible, by wrapping the flower node in damp Osmunda and keeping it warm and damp, to force the growth of a new plant.

Dendrobium, of sympodial growth, will put forth little plant-lets, complete with bulb and roots, at the slightest provocation.

These plantlets develop from the cane-like flower stems. If the beginner keeps his Dendrobiums, especially the deciduous type, too warm and moist during the dormant season they will waste their strength in plantlets and fail to bloom.

Many commercial growers pick the entire cane on flowering and, after cutting off the blooms, lay the canes on damp, warm sand or gravel to allow plantlets to develop from the dormant eyes. Dendrobiums are easily divided or grown from seed.

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