Orchid Basics

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Orchids

Orchids are one of the largest, most diverse, and most ancient families of flowering plants on earth. Currently, scientists estimate there are 25,000-30,000 species of orchids with 120,000 additional hybrids. Orchids come in an enormous variety of sizes, shapes, and colors. Sizes range from Platysteles, with flowers the size of a grain of sand at half a millimeter, to Paphiopedilums (commonly known as Ladyslippers) with petals that extend more than 2 feet (0.6 meters.) Orchid flower shapes range from simple-looking, triangular Masdevallias to complex, Rube Goldberg-like Stanhopeas that present a floral maze to their pollinators. They boast most every color except true black, and some have scents that are studied extensively by perfume makers. Orchids also give us vanilla, one of the world's most popular flavorings.

Once only available to wealthy gardeners at great expense, technological advances in the past few decades have significantly lowered prices and made many orchids widely available. Sold as cut flowers or blooming plants, orchids are one of the most popular plant families in the horticulture industry.

What is an orchid?

Despite their incredible diversity, orchid flowers do share several defining traits:

Fused stamens (male reproductive parts) and pistils/carpels (female reproductive parts.) These male and female components are connected in a small structure called a column.
Pollen is in the form of pollinia, which are small yellow clumps that contain tens of thousands of pollen grains massed together. Orchids have 2, 4, 6, or 8 pollinia.
Orchid flowers contain 3 petals and 3 sepals, with one highly modified petal called the labellum (flower lip.) Often the labellum is the most ornate part of the flower.

Bilateral symmetry, which means that you can draw a line down the middle of the flower, and the halves will be mirror images.

There are about 900 recognized genera in the orchid family.[1] Some genera contain only a few species, but others like Bulbophyllum contain 2700 separate species.[2]

Some of the most commonly cultivated genera include:

Cattleya
Coelogyne
Cymbidium
Dendrobium
Epidendrum
Laelia
Masdevallia
Miltonia
Odontoglossum
Oncidium
Paphiopedilum
Phaius
Phalaenopsis
Vanda
Zygopetalum

Hybrids

Although there are a few natural hybrids, over 120,000 orchid hybrids have been created by humans, and more are created every year. With numerous subfamilies of closely related orchids, many can be interbred. Expert growers can choose parent plants based on traits they want to emphasize, such as color, shape, or scent. Hybridization can also produce stronger, more resilient plants, with longer lasting and more frequent blooms.

Many commonly grown hybrids are crosses of different species within the same genus. When hybrid parents come from different genera, the species names are combined to indicate the new cross. Examples include:

Doritaenopsis: a cross between Doritis and Phalaenopsis
Miltonidium: a cross between Miltonia and Oncidium

Sophrolaeliocattleya: a 3-way cross between Sophronitis, Laelia, and Cattleya

Hybrids with parents from 4 or more different genera are given a new name that ends with “-ara,” such as Potinara or Wilsonara. The initial part of the name often comes from the name of the grower who created the hybrid.

Where do orchids grow?

Orchids are a global plant family. They grow on all continents except Antarctica, and everywhere but the driest deserts and coldest mountaintops. Many have their homes in tropical rainforests, which is where the most commonly known orchids originate. The rain forests of Central and South America, Africa, and Southeast Asia each contain thousands of different species. Other orchids come from temperate and even polar regions of the world. All European countries and all American states are home to some orchid species. Most orchids native to temperate climates are much smaller and less colorful than their tropical counterparts, and are not typically cultivated.

Orchid Environments

Many orchids do not grow in soil. They grow up in the jungle canopy, where they live as epiphytes (air plants) with their roots attached to tree trunks and limbs. Epiphytic orchids are not parasites, but like ferns and bromeliads, they use their host tree for support. With abundant plant and animal life around them, the rainforest provides fertilizer and water. During dry seasons, high humidity keeps plants from drying out. Most epiphytes are native to the tropics.

Lithophytes grow with their roots attached to rocks. Orchid roots can cling to large rocks or cliff-faces. Some grow in plant debris that collects in crevices. Most lithophytes are also native to the tropics.

Terrestrials grow in the ground in soil, peat, or leaf litter. Many terrestrial orchids grow in damp locations, such as alongside a stream. Some terrestrials are native to the tropics. Most orchid species native to temperate regions of the world are terrestrials.

Orchid plants

With so many thousands of separate species adapted to so many different types of environments, orchid plants come in many different sizes, shapes, and forms. No single description can suffice for such diversity, but there are some common traits:

Orchids follow one of two growth patterns:

Sympodial, where new growth extends laterally from the old. Examples include Cattleya, Dendrobium, and Maxillaria.
Monopodial, where new growth extends up a central stem. Examples include Angraecum, Phalaenopsis, and Vanda.

Many orchids live in areas that experience dry periods, and therefore they may have thick, succulent leaves capable of storing water. Some sympodial orchids have thickened stems at the bases of their leaves, called pseudobulbs, which hold water. Pseudobulbs can be egg-shaped, spherical, or resemble swollen stems.

Many orchids have roots covered with velamen, a highly absorbent layer of tissue that helps absorb moisture and nutrients. Newly-grown velamen is shiny, with a white or light green color.

Terrestrial orchids from temperate climates often have swollen underground roots, or tubers, to store water and nutrients during dormancy. Leaves and stems die back, and are re-grown each year.

Caring for orchids:

The enormous diversity of the orchid family precludes any single recipe for care. The basic care information presented here covers cultivation for some common genera that are available commercially.

Light

Orchids need sufficient light to thrive and bloom. Light levels for some commonly grown genera:

full sun: Vanda, some Epidendrum
bright light with some direct sun: Cattleya, Dendrobium, Oncidium

shade with little or no direct sun: Masdevallia, Paphiopedilum, Phalaenopsis

Some orchids can be grown under artificial light, but others demand natural light.

Water

Water needs vary tremendously among different species. Variations in temperature, light, and humidity must be factored in as well. Epiphytic orchids require excellent drainage, and their roots will quickly rot if they are kept too wet or left sitting in water. On the other hand, some terrestrial orchids, such as Sobralias, enjoy very moist soil during summer.

daily water: Masdevallia, Odontoglossum, Vanda
water several times a week: Dendrobium, Epidendrum, Paphiopedilum, Phalaenopsis

water weekly: Cattleya, Laelia

Humidity

Orchids enjoy high humidity around their leaves, roots, and flowers. Ideal humidity levels range from 50%-75%. Low humidity levels can cause flowers to quickly wilt, invite pests, and can eventually kill the plant.

Temperature

Temperature needs vary according to species. While many tropical orchids come from hot, steamy jungles, many other species live high on the cool slopes of the Andes, Himalayas, or other mountain ranges. At elevation, they live in cloud forests with constant fog and rain.

Orchids are usually grouped into 3 temperature ranges:

Warm growers need warm days with nighttime minimums of 60°-65°F (16°-18°C.) Examples include Cattleya, Phalaenopsis, and Tolumnia.
Intermediate growers need mild days with nighttime minimums of 50°-55°F (10-13°C.) Examples include Epidendrum, Oncidium, and Phaius.

Cool growers need cool days with nighttime minimums of 40°F (4°C), although some can handle light freezes. Examples include Masdevallia, Odontoglossum, and many Pleurothallis.

All orchids require slightly cooler nighttime temperatures.

Fertilizer

Orchids grown in cultivation can derive some nutrients from the breakdown of their potting material (usually moss or bark.) Growers often add specialized orchid food, which includes nitrogen, potassium, phosphorus, and other nutrients.

Air Movement

All orchids require good air movement. Still air encourages damaging microorganisms and insect pests. Epiphytic orchids especially need good air movement around their roots.

Dormancy

Many orchids experience a dry season in their native environments. This includes all orchids with pseudobulbs. In cultivation, these plants typically go dormant in the winter. Water and fertilizer should be reduced at this time.

Repotting

When grown in pots, orchids usually need to be repotted every 2 or 3 years. Potting media decomposes over time, blocking critical air circulation around roots. At the start of the growing season (usually in spring,) growers:

remove the plant from its pot, and discard the old potting material,
clean the orchid’s roots, and remove any dead or damaged ones,
reuse the flowerpot, or find a new, clean one based on the size of the remaining root-ball,
replace the orchid in the pot with new potting material,

allow the plant for recover for a few weeks in shadier conditions.

Orchid reproduction

Like other flowers, orchids reproduce when pollinators transfer pollen to another orchid flower. Orchids often have a specific pollinator relationship with one type of insect or bird. Their flowers have evolved to entice that pollinator to visit the flower and pick up the sticky pollinia. When the pollinator visits another flower, it transfers the pollinia, and the second flower is fertilized.

Upon fertilization, seeds start to form. Orchid seeds take weeks or months to develop inside a seed pod. When the seeds are ready, the pod bursts open, sending the miniscule seeds floating in the air. There can be hundreds of thousands of seeds in each pod, but only a small percentage will land where the growing conditions are just right, and even fewer will grow to maturity.

In order to germinate, orchid seeds need a mycorrhizal fungus. Since the seeds are so small, they carry no nutrients, but instead form a symbiotic relationship with this fungus. It provides food for the young plant.

Technological Advances

In the first half of the 20th century, botanists developed artificial nutrient solutions that could substitute for the fungus. This greatly improved success rates for orchid breeders. The second half of the 20th century saw tremendous innovation with orchid cloning, or meristem propagation. Today, many of the most commonly sold orchids are clones that originated with a tiny piece of tissue from a single plant. However, not all orchids can be cloned, and some must be grown from seed.

Asexual Reproduction

Some orchids, such as Arundina, Dendrobium, and Epidendrum, can reproduce asexually by making “keikis,” which is the Hawaiian word for “babies.” These small offshoots can be separated from the mother plant when they have strong enough roots, and planted to grow into maturity.

Orchid growers can also divide healthy adult plants and re-pot each division separately. This method of asexual reproduction creates multiple divisions of the same plant.

Uses for orchids

Many types of orchids are popular as cut flowers, corsages, and houseplants. Orchid industry sales contribute millions of dollars annually to the economies of many countries:

Netherlands
Singapore
Taiwan
Thailand

USA (especially the states of Hawaii, California, and Florida)[3]

There are only a few orchids that have commercial food value. The most important is vanilla, which was originally cultivated by native peoples in Mexico. Natural vanilla flavoring comes from vanilla beans, which are the cured seedpods of the tropical orchid.

Around the Mediterranean, several species of the Orchis genus are used to make salep. Dried Orchis tubers are ground into flour, and then made into salep drink, pudding, and even a form of ice cream.

Conservation

Orchids all over the world face extinction dangers from:

Habitat destruction: Rainforests in Central and South America, Southeast Asia, and Africa are a minute fraction of their original sizes, and continue to be destroyed at an alarming rate. Many countries do not protect their old-growth forests, and even in countries where orchid habitats are protected, illegal logging and burning continue. A single felled or burned rainforest tree can destroy hundreds of orchids that were attached to its branches. With new orchids discovered every year, it is likely that some species have already been destroyed that were never scientifically identified.
Unique pollinators: Since orchids frequently have a unique species of insect or bird acting as their pollinator, they are at great risk if their pollinators become endangered or extinct.
Over-collection: For centuries overzealous orchid collectors have done great damage by removing orchids from their native habitats and destroying their homes. Sadly, rare orchids still command a high price in illegal trading. International treaties, like the 1973 CITES agreement, protect wild orchids, but often enforcement is lax or nonexistent.

Global warming and climate change: With global temperatures quickly rising at the start of the 21st century, orchid populations face increasing danger. Even orchids that were believed to be safe in their native environments have uncertain futures. Climate change can cause alterations in rainfall patterns, loss of pollinators, and introduction of new pests and diseases. These can all threaten the survival of orchids.

Numerous governmental and private organizations are working to preserve orchids and their habitats.

Orchid Conservation Alliance
Orchid Conservation Coalition
Orchid Conservation International
OrchidMania
World Land Trust

References

Books

Botanica's Orchids, JoAnn Holliman, Managing Ed., Laurel Glen Publishing, San Diego, CA, 2002.
Bulbophyllums and Their Allies, Emily S. Siegerist, Timber Press, Portland, OR, 2001.

Easy Orchids, Mimi Luebbermann, Chronicle Books, San Francisco, CA, 1996.

Flora’s Orchids, Isobyl LaCroix, Ed., Timber Press, Portland, OR, 2005.
Growing Classic Orchids, Mike Tibbs and Ray Bilton, Sterling Publishing, NY, 1990.
Growing Orchids, James B. Watson, Sr. Editor, 2002 rev. ed., American Orchid Society, Delray Beach, FL.
Growing Orchids, David P. Banks, Kangaroo Press, Sydney, 2001.
Growing Orchids in Your Garden, Robert GM Friend, Timber Press, Portland, OR, 1994.
Illustrated Encyclopedia of Orchids, Alec Pridgeon, Ed., Timber Press, Portland, OR, 1992.
Little Book of Orchids, Genevieve Carbone et al, Flammarion, Paris, France, 2002.
Manual of Orchids, Joyce Stewart and Mark Griffiths, eds., Timber Press, Portland, OR, 1995.
Orchids As Houseplants, Rebecca Tyson Northen, Dover Publications Inc., NY, NY, 1976.
Orchids Simplified, Henry Jaworski, Houghton Mifflin Co., Boston, 1992.
Simon & Schuster's Guide to Orchids, Alberto Fanfani, Simon & Schuster Inc., NY, NY, 1989.
Sunset Orchids, Marianne Lipanovich, Managing Ed., Sunset Books, Menlo Park, CA, 1999.