Orchids

Mad about Orchids

Orchids are some of the most intriguing of all flowering plants, with amazing adaptations, variations and survival tactics among species.  That’s why we are so crazy for them!  The Orchidaceae, or orchid family, is one of the two largest families in the plant kingdom, approximately 25,000 natural species found on all continents except Antarctica.  They come in every imaginable size, color, scent and shape, and breeding has produced an even larger array of orchids—more than 30,000 hybrids!

The history of orchid cultivation traces back to the 1730s in Europe, although the first classification of orchids was around 300 B.C. by Greek philosophers.  But the real status explosion of orchids occurred somewhat by accident in the early 1800s in Europe.  An English plant collector, Mr. William Cattley, received a shipment of tropical plants and was intrigued by an odd, sturdy plant material (some yet-undiscovered orchids) used for padding the package.  He succeeded in growing the orchids out of curiosity, and received the first blooms in 1818.  They were named cattleya in honor of the caretaker.   This fascinating new flower created much wonder, which quickly developed into a craze now known as Orchidelirium. 

The pursuit of orchids was at the height of popularity and style for the 19^th century bourgeoisie, who sent orchid hunters on expeditions to harvest new specimens from the wild.  They were sold at auction in London at staggering prices.  Today, all kinds of orchids are available in plant nurseries and markets worldwide.  Greenhouse hobbyists and home windowsill growers alike are able to enjoy these extraordinary plants and their spectacular blooms.

Many orchids known as epiphytes grow on trees or shrubs for support, while others called terrestrials grow in soil and organic matter in the ground.  Both types produce flowers in a range of colors, from minuscule to 20 centimeters (about 8 inches) in diameter.   An epiphytic plant is one that is able to obtain its water and nutrients from rainfall and decomposing materials.  Epiphytes exist without soil and gather all that is necessary for their growth while clinging to another immobile organism.  Some examples of epiphytic orchid genera are phalaenopsis, cattleya, dendrobium, and oncidium.

Terrestrial orchids are generally found in more temperate regions of the globe, adapted to survive freezing temperatures with energy storage organs.  After winter, the food storage is used to produce new leaves and shoots for another growing season, similar to the seasonal cycle of bulbs.  Another defining characteristic of terrestrial orchids is their special codependent relationship with a soil fungus, or mycorrhizae.  Cymbidium, eulophia, and phaius are examples of terrestrial orchids, and paphiopedilums are semiterrestrial.

Because there are so many types of orchids from almost every corner and condition in the world, it may seem difficult to learn to care for them.  Within the exhibit, you will discover how to distinguish between various genera of orchids, and learn where each group originates in order to understand its environmental needs. 

Growing Media

The most important element of the orchid potting medium is air.  Because many orchids are epiphytes, the roots are designed to be exposed to the environment.  Healthy roots are plump and white with green growing tips.  The ideal mix retains adequate moisture without becoming saturated and allows plenty of drainage and support.  Even terrestrial orchids keep their roots in the upper layer of the soil in order to maintain adequate gas exchange and water penetration. 

It seems that you can raise orchids in almost anything, including rock, glass, clay pellets, perlite, charcoal and even shredded auto tires.  Growers typically experiment with a variety of organic and inorganic ingredients to develop their own recipes, and let the orchids dictate their preferences.  One orchid enthusiast may swear by a particular medium, while another is quite hesitant to use it.  Some common components include pine or fir bark, tree fern fibers, sphagnum moss, coconut husk and clay pellets.  Polystyrene packing material is also a common additive to the bottom of pots to increase percolation. 

As expected, there is a choice of containers in a range of sizes in which to grow your plants.  Clay pottery and plastic pots are popular choices for orchid cultivation. It is also possible to use teak wooden baskets without any medium whatsoever in environments with adequate moisture. 

Orchids in the Desert

Orchids do not grow wild in the arid desert regions of the Southwest, but in other parts of the world some orchids manage to live the desert life.  These orchids are suited for cultivation outdoors in Tucson, at least part of the year.  When they bloom, striking flowers emerge in pinks and yellows or neutral colors on tall, prominent spikes.

The best-known “desert orchid” is Eulophia petersii.  It grows across much of Africa and the Arabian Peninsula.  In Tucson it grows well outdoors when treated as a succulent plant, in well-drained cactus mix and partial sun.  It should be brought indoors in winter to protect it from cold.

Several species of eulophia and oeceoclades are available and usually sold by cactus and succulent nurseries.  A few other arid-adapted orchids such as Cytopodium punctatum and Oncidium cebolleta are promising for desert cultivation. 

Other terrestrial orchids such as cymbidium and bletilla species are not truly arid-adapted but can be cultivated outdoors if a suitable shaded niche is prepared for them.  Doubtless many other orchids have potential for outdoor cultivation in Tucson.  

Although orchids do not grow in the Southwestern desert soil, Arizona does have 26 species of wild orchids.  Most live in Arizona’s mountains above 5,000 feet, but some live as low as 1,200 feet in pine forests, grasslands and along stream banks.  Some are rare, but others are common enough to be seen by the observant hiker, especially after summer monsoon rains coax them into bloom.  All of Arizona’s orchids are protected in the wild, and will not tolerate transplanting.

Paphiopedilum (paff-ee-oh-PED-ih-lum)

Paphiopedilum, also known as paph or lady’s-slipper due to its elegant flower shape, is a subtribe of cypripedium.  Phragmipedium is a similar genus in culture and appearance, but instead is native to Southern Mexico and South America.  Paphiopedilums originate from the mountainous regions of Southeast Asia and grow in moist forest debris, mossy cracks in rocks and sometimes in trees.  In their natural habitat, paphs are classified as terrestrial or semiterrestrial orchids, found in intermediate to tropical climates.

This genus is divided by temperature into cool- and warm-growing paphiopedilums.  Those in the former group prefer night temperatures near 55 degrees, and can even withstand dips into freezing, and days up to 80 degrees.  Warm growing paphs (such as brachypetalum and maudiae types) appreciate day temperatures around 80 degrees, and nights in the 60s—obviously better suited for Arizona’s warm climate.  Unlike their cool counterparts, warm-growers do not need a drop in night temperatures to bloom, nor a large diurnal range (a difference in day/night of at least 20 degrees) as the cool multifloral species do. 

Low-intensity light is sufficient for paphs, perhaps a shady window with indirect sun.  These orchids grow in moist conditions, ideally at 50 percent humidity, which can pose a challenge for growers in arid climates.  Recommended for arid climate cultivation are common barbata and maudiae types, which typically produce one flower per stem.  Additionally, the beautiful leaves of these varieties are frequently mottled, spotted with light or dark green. 

The Orchid Stud-Book in 1909 noted that the variety of species in this group “far outnumbers those in any other, largely due to the ease and certainty with which seedlings can be raised.”  The flexibility of paphiopedilums makes work within this genus quite rewarding, and today there is a prosperous industry with breeding and creating hybrids.  Orchids are capable of interbreeding between two or more groups, resulting in multigeneric hybrids.  So far, up to seven distinct genera have been combined, resulting in one unique hybrid orchid. 

Phalaenopsis (fal-eh-NOP-sis)

In 1852, a Dutch botanist discovered a new genus and named it phalaenopsis, derived from the Greek phalaina, meaning moth, and opsis, meaning appearance or vision.  Each broad flower, of which there can be dozens on a single blooming plant, resembles an airborne moth.

Members of this group of orchids are native to the Far East and especially thrive in the Philippine islands.  Phalaenopsis’ natural tropical setting remains consistently warm throughout the year, with medium to high humidity.  The plants favor relatively low light conditions where they receive frequent watering; therefore they are frequently found on trees or rocks.

You might think Tucson’s arid climate would make it hard to grow phalaenopsis, but they are one of the most adaptable and easy to grow of our indoor orchids.  Phals are produced in a range of colors, and are usually available anywhere orchids are sold.  They are relatively tolerant to less than optimum humidity, if proper shade and adequate water is provided.  An east-facing window is best, and some growers place them on a pebble-filled water dish for extra moisture.  Maintaining a temperature between 62 and 85 degrees is easy since many homes stay within this range.  The plants appreciate air movement, which occurs naturally in a trafficked room. 

You can persuade healthy plants to bloom a few times per year, but phals naturally bloom from late winter to spring.  Although phalaenopsis is generally not a genus that we associate with scent, there are a surprising number of species and hybrids with fragrance.  Professional breeders are trying to expand that list, with scents similar to rose, freesia, lemon and spicy cinnamon.

Vanilla—The Tropical Orchid of Commerce

The vanilla orchid (Vanilla planifolia, V. pompona) is native to Mexico and has become an important agricultural crop around the world.  Though we refer to its fruit as a “vanilla bean,” it is in fact a pod-shaped capsule that matures after several months on the vine.  It is one of the most labor-intensive crops and as a result vanilla is an expensive spice.

The yellow vanilla flower lasts only one day and must be pollinated to produce a seed pod.  Both male and female parts grow on the same flower, but assistance by an insect, bird, or human is necessary in order to transfer male pollen to the female stigma.  The resulting seed pod will eventually be harvested, fermented, and cured in order to extract the essential oils.  Most of the fragrance resides in the seeds and the oily liquid around them.

Vanilla’s origins are in southeast Mexico and Guatemala. Today, the most important exporters are Indonesia, Madagascar, Mexico, and Reunion Island.  Vanilla was introduced to the conquistador Hernán Cortés by the Aztec ruler Montezuma in 1520, and then was brought to Europe by Cortés.

Cattleya (cat-ley-ya or cat-lee-ya)

Called the “queen of the orchids,” cattleya may be the most popular genus of orchids.  These elegant plants can be found growing epiphytically high in the trees of tropical Brazilian forests in the Andes Mountains.  Although they thrive in conditions of bright light and high humidity, cattleyas, like many types of orchids, have developed water storage organs called pseudobulbs.  This adaptation allows the plants to withstand periods of dryness in the breezy treetops.

Cattleya was the first successfully cultivated orchid by Mr. William Cattley in 1818, then the first cross was performed in 1859. Since then, numerous hybrid genera have been created to manipulate various characteristics of the flowers.  For example, a standard sophronitis produces flowers with intense colors and round shapes.  When crossed with a cattleya, the resulting flowers took on these characteristics, and thus it is called a sophrocattleya (SC).  The genus laelia contributes a compact, multi-floral attribute, producing a laeliocattleya (LC).   The outcome of numerous hybridizations is a broad range of flower colors and shapes in cattleyas.

Plants of this genus may be grown successfully at home if suitable light and humidity are provided.  This genus appreciates more sunlight than other types of orchids, which can be obtained from a south, east, or west window.  Humidity can be increased in the plant’s immediate area by placing the pot on a pebbled tray with a little water, or regular misting of the area.  To mimic the tropical canopy environment, daytime temperatures are ideal between 85 and 90 degrees, and 55 and 60 at night.

Dendrobium (den-DROH-bee-um)

The name of this genus means “tree life,” derived from the Greek word dendron meaning tree, and bios meaning life.  Plants in this group are well adapted to the epiphytic lifestyle.  They take advantage of the high light levels and send out large masses of aerial roots to absorb the moist air.  All dendrobiums are native to the East; China, Japan, southern India and northern Australia.  They feed heavily on composting leaves and tree litter on branches.

During the summer, dendrobiums love plenty of heat, light and water.  They produce storage organs for food and water that resemble bamboo canes. Soft caned types called nobile dendrobiums appreciate cooler conditions, while hard caned plants grow in warmer areas.  Some dendrobiums need periods if dormancy, or rest, during the dry, cooler winter season. The canes sometimes look dead and dry during dormancy, and then suddenly impressive yellow, pink or white blooms burst forth from the seemingly lifeless plant.

Oncidium (on-SID-ee-yum)

Oncidiums are members of the subtribe Oncidiniae, which also contains odonoglossums, brassias and miltonias.  Although the statement is debatable, oncidiums produce some of the most magnificent shows of flowers.  Breeders of this family of orchids aim to create incredible color combinations on large sprays of flowers.  Another objective when hybridizing is to produce a plant that can remain in bloom for most of the year. 

Similar to cattleya, they are native to Central and South America, most abundant in high elevations between 5,000 and 9,000 feet.  The brisk, moist air from the ocean at such altitudes explains why many species are cool-growing.  The mean annual temperature where oncidiums naturally occur is about 55 degrees with 50 to 60 percent humidity. Hybrids have been bred to withstand higher temperatures for easier cultivation.

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