Orchidaceae - Orchid
DESCRIPTION: This group consists of 25,000 to 30,000 different species or wild types that are found throughout the world including tropical forests, semi-desert regions, near the seashore and the tundra. Although most Orchids are found in tropical regions, some such as Cypripedium passerinum and guttatum and Coeloglossum virdie, bloom within the Arctic Circle. Some Orchid groups are pantropical, meaning they grow in many different countries, while some are endemic, which is to say they are restricted to certain countries or even certain habitats within a country. In addition to the wild species, about a hundred thousand hybrids have been raised. This family probably contains the most varied plants and flowers. Their beauty, strange shapes and long life attract an abundance of attention. Their sizes vary greatly; a whole plant in bloom may only be the size of a nickel, others may weigh a ton and have flowers with wispy petals 30 inches long or sprays of smaller flowers 12-14 feet long. Their blossoms come in practically every color, although there are no truly black orchids; however, some are colored so darkly they appear black. The beautiful flowers consist of a corolla of three petals, one of which, the lip (labellum) may be frilly or plain, large or small, long and thin, or shaped like a bucket. One interesting feature that distinguishes the orchid from other flower groups is the union of the male parts and female parts of the flower. Orchids have three pistils and three stamens and they are fused into a column (gynostemium). Most orchids have only one fertile stamen, although slipper orchids such as Phragmipedium, Paphiopedilum, Selenipedium, and Cypripedium have two fertile stamens. The pollen grains of the fertile stamens are clustered into packets called massulae or more sticky units called pollinia. Orchid groups are ordinarily defined by the number of pollinia present. Some orchids are found growing atop trees and some live completely underground, such as Rhizanthella gardeneri, one of two Australian species. Only the flower of this plant peeks above the surface to allow pollination by small insects. Orchids have two basic habits of growth. Sympodial orchids, such as Cattleyas, form a horizontal stem called a rhizome that produces new shoots from buds. Monopodial orchids, such as Vandas and Vanilla, have no rhizomes or pseudobulbs, but produce an erect or pendent stem with leaves growing continuously from the same growing point. Orchids are also classed as epiphytes (those that grow naturally on trees, etc.), terrestrial (those that grow in the soil), subterranean (those that grow beneath the surface of the growing medium),or lithophytes (those that grow on the surface of rocks). The leaves of epiphytes usually persist on the plant from year to year, but leaves of terrestrials often die at the end of the growing season. Leaves may be plicate (folded many times longitudinally) or conduplicate (folded once in the middle). Plicate leaves are always thin, but conduplicate leaves may be thick, fleshy, and leathery. Some leaves are terete, (pencil-like and round in cross-section). Orchids have interesting pollination techniques. Although some Orchids are self-pollinated, the remainder are pollinated by bees, wasps, gnats, flies, moths, butterflies, ants, and birds. These animals are attracted in different ways often to a specific species. Some bees are attracted to certain groups of Orchids because of their scent. The bees work over the flowers collecting scented droplets, thus pollinating the flowers. Some flowers resembling female insects by appearance and scent. The males are tricked and attempt to mate with or steal away the "female insect" and thus flies away with pollinia and/or has deposited pollinia onto the stigma from another flower. Some flowers have sensitive labellums which closes against the column as soon as it's touched. The trapped insect must squeeze through a slim tunnel between the column and tip of the labellum to escape, consequently attaching pollinia to its body. Some blossoms are brightly colored to attract butterflies, while some are dull, but fragrant at night, in order to attract moths. Some are brightly colored and supplied with sweet nectar to attract birds.
POTTING: Orchids aren't as difficult to cultivate as people seem to believe. Buy Orchids that suit your growing environment. If you live in a tropical climate, buy warm-growing plants rather that woodland forest or alpine plants. You can, with certain limitations, alter the growing conditions of your area to suit your plants by raising the humidity, allowing more ventilation, and altering lighting conditions to allow more or less light. By checking your plants regularly (such as for signs of yellowing or dropping of foliage, failure to blossom, leaf-spotting fungi, or insect invasion), you can adjust their conditions accordingly. Lighting is very important to a plant's survival, for without it photosynthesis cannot take place and the plants will die for lack of nourishment. This is a common problem with houseplants. Lack of light will cause the foliage to yellow and droop. Mistaken for a need for water, the plant is drenched and because of low lighting the plant can't even begin to process the overabundance of water, therefore rotting to death. To prevent this, purchase plants adapted to your lighting conditions, whether for a windowsill, artificially lighted bench, or greenhouse. The amount of light or shade an Orchid requires depends upon where the Orchid lives in nature. The temperatures an Orchid requires also depends on where it was growing in the wild. Orchids are generally classified as warm-growing (requires a minimum night temperature of 65º F or 18º C), intermediate (min. night temp. of 59º F or 15º C), or cool-growing (min. night temp. 54º F or 12º C & max. day temp. 75-77º F or 24-25º C). A temperature fluctuation of about 10º F is necessary for most Orchids to flower. This can be achieved by opening a window at night or by lowering the thermostat. When and how much to water is the most difficult to decipher. The amount of humidity present, the growing medium and container used, and the amount of light, temperature and ventilation are all factors to take into consideration. Additionally, many Orchids have "resting periods", in which they receive little or no water. Generally, you want to water only when they are actively growing, which is ordinarily at the beginning of spring until they have finished producing flowers. The best way to tell if an Orchid needs water is to feel just below the surface of the potting medium; if it's moist, wait. Watering should be increased the more light is admitted, the higher the temperature, more air circulation, lower humidity, use of clay pots (clay pots dry out faster) with good drainage and an open potting medium. Water enough so water runs through the drainage holes at the bottom of the container. This will wash out any accumulated salts in the medium that will burn the roots. You should fertilize your plants only when they are in active growth. It is recommended that you water before fertilizing to allow the roots to absorb the fertilizer quickly preventing them from being burned. Another way to prevent this is to use only half the concentration recommended. It is much better to fertilize with half the strength every watering than to shock the plant with full-strength every once in a while. Balanced fertilizers (20-20-20 or 10-10-10; respectively nitrogen, phosphorus, and potassium) are best for tree-fern fiber, osmunda fiber, sphagnum, and inert potting media such as gravel, rockwool, lava rock, etc. Higher concentrations of nitrogen, such as 30-10-10, are often sold for plants potted in fir bark, while others, such as 10-30-20, have higher amounts of phosphorus to promote better flowering. The humidity in your growing area can be measured with a tool called a hygrometer. The humidity should be above 50% and ideally 70%. Misting the plants with water is a brief way to raise the humidity; however, make sure the plant is dry by night to prevent the growth of bacteria and fungi. Another good way to ensure proper humidity is to set the plants an inch or so above water on gravel filled trays. The water level should be below the surface of the gravel so that the pot isn't ever in contact with the water. Grouping plants will also raise the level of humidity in their immediate surroundings. Room humidifiers are also very effective. Adequate ventilation is also important in order to keep uniform temperatures and stagnant air from spreading disease. Ceiling fans, AC vents, and small fans that aren't blowing directly on the plants are useful in gently circulating air. Orchids can be grown in a number of media, both organic and inorganic. The two most common are fir bark and tree-fern fiber, used in various combinations with perlite or pumice, redwood bark, sphagnum bark, charcoal, lava rock, and cork. Tree-fern, bark, and charcoal are graded as fine, for seedlings and tiny plants; coarse, for large sympodial Orchids (those that grow horizontally) and Vandas; and medium, for everything else. The mix used for terrestrials should consist of various proportions of coarse sand, loam, and leaf mold with traces of blood and bone meal. Some groups will require more specific mixes. There are numerous ways to pot your Orchids; pots, slabs of cork or tree-fern, natural mounts on twigs or branches, and baskets of sphagnum are all good choices. The growth habit and cultural needs of your Orchids will determine which one your choose. The flower inflorescences of Stanhopeas grow through the potting medium to peak out below. Therefore, a sphagnum lined basket should be used. Vandas and Ascocentrums, as well as their hybrids, Ascocenda, should also be planted in baskets with coarse bark or charcoal placed around the roots. Some species need to dry out completely between waterings and are best grown in cork or tree-fern slabs, while those that need more moisture should be grown in clay or plastic containers. Remember when watering that clay pots dry out faster than plastic pots. When potting an Orchid, the diameter of the top should be no larger than to allow one or two years of growth. Sympodial Orchids (those that grow horizontally) should have enough space between the youngest shoot and the rim of the pot to allow for two years of growth. The containers should be filled about one-third with stones or Styrofoam pellets. Add enough potting medium so that the plant is one or two centimeters below the rim. Then fill in around the plant with medium, pressing it down firmly as you go along. Large plants may need to be clipped or staked to immobilize them until they are established. Monopodial Orchids (those that grow vertically instead of horizontally) need to be positioned in the center of the pot and not to one side as Sympodial Orchids. The lowest leaf should lie just above the potting medium. When Orchids grown in baskets outgrow their container, they aren't removed, which can damage their roots. Rather, the basket is soaked in a bucket of water for a few minutes. The basket is then set within a larger basket and the roots wrapped around the inside of the larger basket. The two baskets are wired together and a wire hanger is added. Epiphytes, which need more air around the roots and drier conditions, should be grown on slabs of cork bark or tree-fern fiber. Place the plant on the mount cushioned by a small pad of osmunda or sphagnum moss. Wire the plant through the slab to the back of the mount and tighten. Some people use staples instead of wire. Attach a hanger and place the plant in a fairly shady location until well established. Remember to always insert a plant label with the name of the Orchid and the date of repotting. When you repot, remove shriveled pseudobulbs and leaves and snip off dead, brown, and mushy roots. Healthy roots are firm and white with well-defined tips. Repotting, is a good time to propagate by division. This will be discussed further in the propagation section.
PROPAGATION: Using a sterilized razor blade, knife, or pruning shears, most Orchids can be reproduced by division. The utensil can be sterilized by holding it over a flame. Sympodial Orchids (those that grow horizontally) can be divided by cutting the rhizome so that each division has three or more growths and one actively growing lead. Backbulbs may also have dormant buds and should be potted up separately. Monopodial Orchids (those that grow vertically) cannot be divided in this way. Many of these kinds, such as Phalaenopsis species and hybrids, produce offshoots called, keikis, at nodes along the inflorescence axis. When the roots of the keikis are a few centimeters long, the little plants can be potted up in the same way as the parent plant. Older plants that become top-heavy can be severed, the top half with its aerial roots moved to another pot or basket.
The development of endosperm in Orchids usually stops at an early stage if it forms at all. Endosperm is a tissue that nourishes the embryo. At maturity, the seed consists of an embryo, a seed coat, and little else. Since there is a lack of endosperm, in nature the embryo is nourished by a certain fungal strain. The embryo obtains carbohydrates and mineral nutrients from a mycorrhizal fungus; therefore, this fungi is necessary for germination. Orchids can be germinated in glass flasks on agar with the same sugars ordinarily produced by the fungi along with some mineral nutrients.
VARIETIES - Varieties will be mentioned below in alphabetical order and will have a brief description beside each name. Those that are linked have photographs. Of course, not all the Orchids are mentioned yet, as there are so many. This site is continuously under construction; therefore, entries will constantly be made.
Click on a species to view the photographs.
AERIDES: 19 species. Produces racemes of fragrant flowers in combinations of white, purple & pink (rarely yellow). With the exception of A. krabiensis (lythophyte), species belonging to this group are large epiphytes. They grow best in baskets. Need bright light, frequent watering & heavy feeding. Vining species should be watered daily.
ANGRAECUM: About 200 species. Green or white flowers. Monopodial growth & mostly epiphytic. Grow best on bark & in baskets; some larger plants grow well in pots. Need cooler conditions after flowering. Origin-tropical Africa, Madagascar & adjacent islands, & in Sri Lanka. Temp. & light (or shade) should be appropriate to the origin.
ASCOCENTRUM: About 10 species. Thick, erect racemes of brilliant orange, red, cerise, yellow flowers. A pumilum prefers cool temps. & shade; others require intermediate to warm temp., bright light and plenty of water. Grown in baskets, pots, or mounted on slabs.
BRASSAVOLA: 17 species. The labellum of the long-lasting, fragrant flowers is tightly rolled around the column to form a tube. The other petals are slender and/or ribbon-like. These epiphytes need intermediate temps. in a humid atmoshpere.
BRASSIA: 29 species. Produce inflorescences from the sheath at the base of a pseudobulb. The sepals are very long and spreading. Most species are epiphytic and need intermediate temps. in a humid atmosphere.
BROUGHTONIA: 5 species. Brightly colored flower parts form a flattened circle. At low elevations, these species are epiphytes. They need warm conditions with bright light and light watering.
CATTLEYA: 48 species. These epiphytes are mostly found growing in the tops of tall trees in a moist to wet forest. They can be grown in intermediate temps. with plenty of water during the growing season and less while dormant.
COELOGYNE: More than 100 species. Sympodial epiphytes. Species having tightly clustered pseudobulbs may be grown in pots; others should be mounted on slabs to minimize root disturbance. Needs bright light, but not direct sun, which will burn foliage. Intermediate to warm-growing species need water and fertilizer regularly throughout the year. Cool-growing species need a rest when new growths mature and until new roots appear.
CYCNOCHES: 23 species. Deciduous leaves. Inflorescences consisting of unisexual flowers. Three or four, fleshy female flowers having short, thick column with a club-shaped tip and three wide hooks. Five to thirty, thinner male flowers having longer, thinner column with a device for throwing pollinarium onto the pollinator. These epiphytic plants grow wild in moist or wet forests. Certain kinds of male euglossine bees are attracted to the strong scent. When a bee visits the male flowers the pollinia are thrown onto the abdomen of the bee and are stripped by the hooks of the female flower when visited. These plants should be grown in warm to intermediate conditions with plenty of water and fertilizer while growing actively. Their resting period should be fairly dry.
CYPRIPEDIUM: About 50 species. Commonly known as Lady's Slippers and Moccasin Flower. They grow wild in the North Temperate regions of North America, Europe, and Asia to Japan and south to Mexico. Species of this group have a creeping underground rhizome and stems with 2-4 leaves. Usually solitary flowers, rarely 2 or 3. Perianth portions are spreading with the dorsal sepal growing erect. The laterals point down behind the lip. The interesting lip is large, concave, and saccate with inrolled edges to produce an inflated structure that protects the reproductive organs. The lip resembles a little slipper, thus the common name. Because these beautiful plants have been thoughtlessly collected, only a few species still exist in the wild, which is such a shame. Most of this group are protected within the country of origin and are rarely seen openly sold; however, there are a few that have been successfully cultivated and are beginning to appear commercially.
DENDROBIUM: Over 1,000 species. Species are extremely variable. They are mostly epiphytes and lithophytes with fleshy or wiry stems that may grow erect or pendant. Racemes of solitary or numerous, tiny to large flowers are produced in every color imaginable, except black. Growing conditions vary from cool to warm, from shade to almost full sun. They should be kept evenly moist when in active growth. While dormant, maintain a humid atmosphere and cease watering or provide just enough water to keep the pseudobulbous stems from shriveling.
DORITAENOPSIS: This is a cross between Doritis and Phalaenopsis.
DORITIS: 3 species. These terrestrials are native to southeast Asia. They need warm growing conditions and an evenly moist medium throughout the year. They will live in medium to bright light.
EPIDENDRUM: Over 1,000 species are found throughout tropical America from Florida to northern Argentina. These Orchids have a slit rostellum and semi-liquied viscidium. The lip of most species is united to the column, forming a tube of nectar that penetrates the pedicel. The cultural conditions are varied, from lowland tropical to high alpine, but most grow well in intermediate temperatures, with light shade and moisture throughout the year. They do not usually need a resting period. Many Epidendrum grow naturally in moss or on humus covered rocks; therefore, they may be grown in very light humus with high leaf content, but always with very good drainage.
GRAMMATOPHYLLUM: About 12 species. These very large epiphytes produce large inflorescences of flowers that come in shades of green, yellow, and brown. Some of the largest species are difficult to grow in the greenhouse, but are beautiful when grown as terrestrials in a tropical garden. In order to flower, they should be provided with high light and plenty of water and fertilizer during the growing season.
LAELIA: 60 species. Their pseudobulbs produce one or two, rarely three, leaves. Erect to pendant racemes of few to many, variously colored flowers are produced. They grow well in well-drained, hanging baskets, slabs, or clay pots. They like cool temperatures, bright light, and good ventilation all year. Even when dormant, they still need the cool temps, bright light and low humidity. In most of the Mexican species a dry, cool dormancy with bright light is required. Watering during this time can kill your plants.
NEOFINETIA: This group consists of monotypic species. They are epiphytes and lithophytes. The leaves of these tiny plants grow fan-shaped. They produce racemes of white flowers with long, slender nectar spurs. These plants need intermediate temps., medium bright light, and even watering. They shouldn't dry out completely between waterings; therefore, a moisture-retaining medium should be used. These plants quickly form basal offshoots.
ODONTOGLOSSUM: About 175 terrestrials or epiphytes native to mountainous regions of South America. This group is characterized by the presence of unifoliate or bifoliate pseudobulbs of a single internode subtended by distichous leaf-like sheaths. The inflorescence is produce from the axils of the sheaths. The lips of the flowers are often large and showy. The flowers come in an array of colors. They naturally grow in wet, cloud forests; therefore, they should be grown in cool to cold temperatures with plenty of water throughout the year.
ONCIDIUM: There are more than 600 species of these mostly epiphytic plants; some happen to grow on embankments and others are only terrestrial. Most of the group can be grown in intermediate temps. in pots of well-drained media provided with plenty of water throughout the year. Some species come from higher elevations and require cooler temps.
PHALAENOPSIS: About 50, epiphytic and sometimes lithophytic species native to throughout tropical Asia from southern India and Nepal east to Papua New Guinea, north to China and Taiwan, and south to tropical Australia. They have very short stems covered with fleshy leaves and an abundance of plump roots. They produce inflorescences that may consist of a few flowers to more than 100. They come in a wide variety of colors and patterns. The species of Phalanopsis may be distinguished by a three-lobed, clawed lip. Phalanopsis are monopodial; therefore, lacking pseudobulbs or similar storage orgnas. Therefore, their medium should always be slightly moist. They should be grown in medium light
RENANTHERA: About 15 mainly large, vining species. Huge, branched inflorescences produce orange to red flowers. Usually the lateral sepals are much larger than the floral parts. The saccate lip has three lobes with the midlobe strongly deflexed. Renanthera need bright light, warm temperatures, and generous, even watering. Smaller-growing plants can be grown pots, but larger species should be grown in baskets, with or without support for their trailing stems.
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