Chapter - 23
Epidendrum

growing orchids

Many epidendrums can be grown outdoors in northern United States for a major portion of the year and can be grown the year round in southern and western gardens. Although their flowers are small, their vigor and robustness make them worthy of a beginning orchidist's attention. The largest flower (Epidendrum cinnabarina) is three inches across; the average diameter is one inch, and several midgets barely reach one-sixteenth inch. Of the 500 known species, only about eighty are grown for their gay colors, extreme floriferousness, or rich perfumes.

The name epidendrum means "upon trees" and is something of a misnomer since a large section of the family is strictly terrestrial, growing rankly over the plains of Central America and the islands of the West Indies. In Costa Rica the tight red clusters of Epidendrum radicans are lovely to look at, but the plants are considered as pests because they invade the lush meadows where cows are pastured. In fact, epidendrums are called the weeds of the orchid kingdom, and invade every section in the tropical Americas where orchids may be found. No other orchid genus can boast of such an incredibly thorough distribution. From Florida to Mexico and south to Panama they are as thick as fleas. They flood South America down to Peru and Bolivia and follow the mountain ranges into Bahia. One of them, Epidendrum conopseum, breaks away from its Florida relations and covers evergreen trees from the coasts of Louisiana eastward to Port Royal in South Carolina; it is the most northerly of all epiphytic orchids.

Epidendrums are at home at sea level or on mountain tops in nearly every conceivable climate and condition. Epidendrum frigidium grows at 13,000 feet and may be blanketed with snow. They grow in muggy swamps, in the semiarid Mexican plains, and in the rain forests of Guatemala where 200 inches of rain is a common occurrence. In the West Indies they are so prolific they form huge tufts on trees, literally strangling their hosts to death. Yet, despite the wide and contradictory conditions under which epidendrums are found, their culture is startlingly simple. It can be reduced to a single category: they are grown best under the coolest possible treatment they can stand. Not all of them, however, are cool orchids; a few are classed as intermediate. But they are hardier than the classification implies and will survive comfortably in lower temperatures.

Botanically, epidendrums are allied to cattleyas, laelias, sophronitis, and brassavolas, with which they have been interhybridized—a demonstration of their close relationships. Oddly enough, no bigeneric epidendrum cross has been commercially important. Their robust quality sometimes has been passed to their progeny, but the flowers are always small. Scientists say that the chromosomes of some epidendrums are different from those of cattleyas and other allied genera. Also, and perhaps more important, orchidists who made the original crosses long ago did not know the value of "backcrossing"; that is, mating the largest hybrid back to the most spectacular parent. An amateur with some knowledge and with patience enough to spend a minimum of fourteen years on orchid breeding might be able to backcross epicattleyas with cattleyas and produce the miracle of a hardy, large-flowered race of orchids.

In most cases the epiphytes are singularly interesting for their toughness toward casual culture in windows, greenhouses, or lath houses; just try to keep them from growing! Their ability to flower regularly year after year is also notable; and they regularly adhere to a blooming schedule which rarely varies more than a few days. While most of the flowers are small, there may be from twenty to several hundred on a stem. Some of the flowers are bizarre in shape and audaciously colored, such as the chocolate-brown and purple combinations of Epidendrum atropurpureum which is known to the natives of Guatemala as the "Boca del Dragon" (Dragon's Mouth). Often the most unpromising flowers will be exquisitely fragrant; one spike of Epidendrum fragrans will perfume a room for days on end.

The terrestrial species, too, are equally unusual and striking. They may be separated roughly into two subdivisions for cultural convenience: those that grow to four feet in height, with stems as thick as your thumb (really modified pseudobulbs); and those that rarely rise above eighteen inches, whose stems are as thin as matchsticks. Many of the tall-growing kinds are perpetual bloomers, growing and flowering every month of the year and lasting indefinitely. The terminal panicles have a rachis which produces new flowers as fast as the old ones wither and drop off. One spike of Epidendrum o'brienianum may carry flowers for four to six months. The smaller varieties have the more customary habit of flowering once a year, but they do so profusely.

Epiphytal epidendrums are grown in osmunda in pots only slightly larger than the diameter of the plants. Other than that, they are treated like cattleyas—in fact, are often grown with them in small greenhouses. Because of their vigor they are excellent and undemanding house guests, and any south or east window will keep them reasonably healthy in all sections of the country, if they get enough winter sunlight.

They do not need the care and attention of other epiphytes. Occasional overwatering and inattention do not injure them as much as one would expect; however, don't try to see how hardy or impervious they may be—it never pays. In the northern states where the temperature drops to 32° or lower and stays there for an appreciable period, they will need winter protection in heated frames or structures. They need humidity, and should be syringed on bright days. But a bit of dryness won't make them lapse; they have thrived on as little as 10 to 15 per cent relative humidity. Propagate them by division.

The epidendrum most often found in cultivation is Epidendrum cochleatum—so named for a fanciful resemblance between one of its petals and the spiral-like shell of a snail. Its yellowish-green flower is borne erect, making it one of the few orchids whose flowers are not upside down. Historically, this epidendrum has the honor of being the first tropical epiphyte to flower in cultivation. Its cousin, Epidendrum jragrans, was introduced to English gardens at the same time, in 1787, but didn't flower until the following year.

The loveliest of the genus are Epidendrum vitellinum and its larger variety, majus. The small pseudobulbs and leaves, together about ten inches high, and the ten to twenty brilliant red flowers on eighteen-inch stems make it ideal for home culture where space is at a premium. It blooms in midwinter and adds a dramatic splurge of color when gayness is needed. As a greenhouse denizen or a plant house guest it has few rivals in the orchid tribe in its ability to take the good with the bad.

The tall terrestrial epidendrums are in one respect not so hardy as the epiphytes: they are quickly and irrevocably injured by prolonged frost. Their tissues are more tender and do not have so high a recuperative ability. However, if air circulation about them is free—if they aren't grown in a fenced area that holds frost—they may not be damaged, particularly if shaded the following day. With orchids, as with other plants, it isn't the frost that is injurious—it is the rapidly thawing ice crystals in the plant that mutilates the tissues. Aside from frost they are rather sturdy about their culture. They will grow in full sun and readily endure a temperature of 105° if plenty of moisture is about their roots. They can take plenty of soil moisture the year round and plenty of water hosed on their foliage during midsummer dry weather.

growing orchids

growing orchids

Their soil requirements are vague; it doesn't seem to make much difference whether the soil is good, bad, or indifferent—whether clay, adobe, sand, or any combination of these types. There is no point, however, in treating them too shabbily. When grown properly in good composts they respond with an abundance of leafy foliage and good heads of flowers that are knocKMuts for corsages and vases. Pot them in a terrestrial compost of*leafmold and decomposed granite or gravel. The clay pots should be just large enough to hold the plants without too much room for further development. They do best in small pots and look better in them.

These cultural conditions hold true also for the short-stemmed species, except that they are less tolerant, more sensitive. They need a lighter compost, some shade, more humidity, and a cool, moist atmosphere in summer. In winter the temperature shouldn't drop below 50°. Epidendrum umbellatum can stand frost for awhile; but the other small species may be fatally injured by so slight a thing as a sudden chilling draft. The small epidendrums are best grown under intermediate temperatures in at least partly closed structures.

The two groups of terrestrials also fall naturally into outdoor and indoor plants. The short-stemmed species don't do well outdoors. The tall species, excepting Epi-dendrum xanthinum, which is purely a greenhouse plant, make excellent bedding plants or hedges in the milder sections of the country. At Balboa Beach in California the local chamber of commerce points with pride to a hedge of Epidendrum o'brienianum carrying thousands of bright red clusters of orchid flowers every month of the year.

As pot plants the tall species may be clumped in large pots for spectacular patio and conservatory decorations. They add to gracious living by blooming their heads off for you. Because you have so many flowers, you don't mind picking a boutonniere for your coat or a flower for your wife's hair. Of course, in all the areas of the country where the thermometer starts a downward trend in September that ends up with snow in December, you can't go in for much more than a spot of summer culture. Nonetheless, crop your tall epidendrums to four or five long stems and put them in a five-inch pot in your largest southerly window. They take up a good deal of room, but no more than sprawling ivy or a lanky geranium—moreover, they have richer foliage and respond to your administrations better than these commonly grown house plants.

All terrestrial epidendrums are propagated by division of the plants into several or more healthy clumps. Often, after the last flower dies on the everblooming species, small shoots appear on the flower stem. If they are near the top they turn into a secondary flower stalk; if near the bottom they become adventitious plants which may be cut off and grown on. Old stems of these species may be cut off and placed in a warm, moist spot. They frequently will develop adventitious growths in the leaf axils. These small plants will bloom in about six months; of course, the flowers will be few in number, but several plants may be placed in a pot to secure a nice full effect.

growing orchids

SEED GERMINATION

Top: Seed Wrapped in Tissue and Stored in Glass Tube

Center right: Seed Bed; Turkish Toweling over Osmunda

Center left: Germination of Seed Over Water Tray, under Bell Jar

Bottom: Seedlings Planted in a Community Pot

If you want to experiment a bit with seed germination, there is no better genus to start with than the tall terrestrial epidendrums. They produce seed—the largest in the orchid tribe—in a matter of three months, and often without any help from you. Ants, thrips, and other small insects have a nasty habit of searching for honey inside the flowers and accidentally carrying a bit of pollen with them which fertilizes the flowers; rain also will knock the pollen into the flower and accomplish fertilization. Germination is completed in about six months, and the plants flower in two years. That is remarkably good time for an orchid, really a most undignified haste. You can germinate seeds by the flask-culture technique, or scattering them on Turkish toweling, or directly on osmunda kept continuously moist. Remember, though, this latter method is not applicable to most orchids, and is not always successful with epidendrums.

For planting the seed, get a new brick and soak it in a diluted vinegar solution to leach out any alkali present. Rinse the the brick in clear water and place it in an enamel pan, one deep enough to have two inches of space between the rim and the brick. On top of the brick scatter a quarter-inch dressing of finely sifted leafmold and sand (equal parts of each), or dust it with the very fine particles that are shaken out of sphagnum moss or osmunda. Add sufficient water—acidulated with phosphoric acid (pH 4.6)— almost to submerge the brick, and set the pan aside until the compost is evenly moistened by the capillary movement of the water. Scatter your orchid seeds over the top of the moist compost—don't cover them; they must be exposed. Cover the pan with a glass pane and set it in a warm, somewhat shaded place. As water evaporates add enough to maintain the original water level. Once in a while spray the seed and the compost with a mist atomizer. Don't spray with force; let the water mist settle slowly onto the compost and the immature plants. Seedlings require much higher humidity than adult plants.

In about six months or longer, when the young plants are about an inch high and have small root systems of their own, prick them out and plant in 3-inch pots of sifted leaf-mold and sand; about five or ten plants may be placed in each pot. Carry them on in a cold frame that is mildly heated or in a warm window, and provide them with some shade, plenty of humidity, and a daily syringing on clear days. When they are five inches tall they can fend for themselves. Pot them separately and grow them as you would adventitious plants.

All in all, if you want to cut your teeth on orchids, there is no better genus than epidendrums on which to do it.

growing orchids

DEVELOPMENT OF AN ORCHID

Top: Seed Pod; Seed; Seedling (Six Weeks)

Center: Seedling (Six Months); Seedling (Sixteen Months)

Bottom: Seedling (Two Years)

They cost little compared with most garden plants and other orchids, and are remarkably tolerant of inattention. In the genus you will find a variety of cultural differences which will give you inexpensively the experience you need in order to go on to the culture of more lovely and exacting orchids.

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