ORCHIDACEAE       ORCHID FAMILY 

INTRODUCTION: The orchid family is a very large group of monocots.  It is one of the most recently evolved plant families.  Divisions among species and general are not distinct and many intergeneric hybrids exist.  Orchids are found in nearly every climatic zone from arctic to tropic and on all continents except Antarctica.  Many are native to higher elevations in the tropics and grow best at cool temperatures year round.  There are both terrestrial and epiphytic types.  Seeds of orchids are extremely small, about the size of particle of dust.  The vanilla orchid is the original source of natural vanilla. 
 Epiphytic orchids are divided into two groups, sympodial and monopodial, based on their stem structure.  Monopodial orchids grow upright and develop side shoots, which also grow upright.  They bear their leaves in two ranks, perpendicular to the stem and do not produce pseudobulbs.  Sympodial orchids often have pseudobulbs, a thickened stem from which the leaves arise.  Their growth is horizontal, the pseudobulbs being attached to a common basal rhizome.  Growth of the pseudobulbs and extension of the rhizomes develops out of the base of the old pseudobulbs.  These pseudobulbs store food and water and enable the orchid plant to withstand periods of drought. 
 Cattleya is the genus most people think of when they hear the word orchid.  Although they come in a wide range of colors and color patterns, the color orchid is named for one of the flower colors found in cattleyas.   Most cattleyas make the large, showy flowers common in corsages.  They are tropical epiphytes with sympodial growth and pronounced pseudobulbs.  They are native to higher elevations in Central America and northern South America.  They grow best in warm, but not hot, conditions and grow and flower best at brighter light, brighter than that preferred by most orchids. 
Dendrobium is a sympodial epiphyte native from India to Japan and Australia.  There are several subtypes with distinctly different cultural requirements.  These include the pseudobulb dendrobiums, evergreen cane dendrobiums, deciduous cane dendrobiums, evergreen phalaenopsis type dendrobiums, and black hairy-stemmed dendrobiums.  Dendrobiums vary in the cultural requirements, some needing uniform moisture, others a period of drought; some needing seasonal changes in temperature, others uniform temperature; some needing diurnal changes in temperature, others not, etc.  Many dendrobiums produce smaller flowers but in large sprays.  Many need a dry period prior to bud development. 
 Laelia is a genus of orchids closely related to the cattleyas. They are epiphytic, evergreen orchids with pseudobulbs.  The flowers of laelias have a distinct resemblance to cattleya flowers. 
 The genus Miltonia is native to Central and South America.  These are the pansy orchids, so named because their flowers resemble the flat-faced pansy flowers.  Culture is similar to cattleyas.  Some miltonias have a distinct preference for cool temperature and most thrive in indirect sunlight.  
 Oncidium is a sympodial, epiphytic orchids native from Mexico to Brazil.  Like dendrobiums, many of the oncidiums produce large sprays of smaller flowers.  Oncidiums have a range in temperature requirements depending on the species, but most do best in when given a lot of sunlight and a rest period of several weeks following the development of their new growth. 
Paphiopedilum is the lady slipper orchid.  It is a terrestrial orchid.  This genus is adapted to a wide range in temperature conditions, some being decidedly tropical and others almost temperate.  They thrive in bright, though indirect light.  They lack pseudobulbs and can not store water. 
 Phalaenopsis is the genus of the moth orchids.  They produce large, moth-like flowers in a plane along the two sides of a long, arching stem.  They are monopodial, epiphytic orchids native to south Asia and Australia to west Africa.  They thrive in a diurnal temperature fluctuation of 65oF night to 75-80oF day.  They grow and flower at lower light than most orchids, often thriving in indirect light.  Moth orchids thrive at high humidity. 
 The genus Vanda is native to southeast Asia.  It is a group of monopodial orchids with either strap leaves or pencil leaves.  Vandas can not tolerate temperatures below 50oF for any period of time and thrive in a very humid setting with good air movement.  They need plenty of water but must have excellent drainage. Most thrive in settings with relatively bright light. 
 Vanilla is a monopodial orchid.  It produces a heavy, succulent vine and is relatively east to grow.  Unfortunately it is one of the more difficult orchids to bring into flower. 

General Care of Orchids:  
   

   

temperature: Most tropical orchids grow best at a uniformly warm, but not hot, temperature.  Some orchids thrive at cooler temperatures.
medium: Epiphytic orchids require good drainage and aeration of their roots.  Coarse media such as tree bark, osmunda fiber or moss mounted on tree bark are common.  If potted in common media, such as the peatlite mix, orchids usually fail to thrive and eventually die.  Terrestrial orchids thrive in a rich, organic medium that drains well.
water: Most orchids grow best in a humid environment with good aeration.  They should be watered to keep the medium moist.  For epiphytic orchids potted in a well drained, airy medium this may be twice a day.  Orchids can not tolerate a wet medium.
light: Orchids occur in many different environments and this affects their light requirements.  Some grow near the tops of trees in rainforests.  They need brighter light than others which may be found growing in denser forests and at lower levels in the tree canopy.  Terrestrial orchids in cultivation are usually found on the forest floor and grow well in moderate light.  Most orchids need protection from hot, midday sun in summer, but could be grown in direct light in other seasons.
fertilization: Orchids need a steady supply of nutrients but can not tolerate salts.  Dilute solutions of inorganic fertilizers are common or organic sources of nutrients are used.
pests and problems: Protecting the roots from rot is essential.  This is done by using the proper medium for the type of orchid that is to be grown.  Pests are relatively few on orchids but diseases of the leaves and stems may be a serious problem, disfiguring or killing them.
grooming: Remove old parts of the plant after nutrients have been translocated to the new growth.
propagation: Seed of orchids is extremely small and is usually planted on an aseptic medium such as agar.  Seed is the only way to propagate some orchids, but others may be propagated by division,  separation and stem cuttings.  Asexual micropropagation, a process commonly called mericloning, is done by excising the meristem of a plant, culturing it aseptically to form a mass of cells and then triggering the development of many plantlets from this mass of cells. 

 

 
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