This research paper will explore the botany of orchids, specific orchids of horticultural significance, and orchids’ growth and environmental requirements.
Within botany the basic structure of the orchid will be covered along with common morphological features and how orchids reproduce. When discussing different types of orchids, a specific form will be used. Within the final section covering how to grow orchids, different methods will be mentioned. Examples of these methods include buying orchids, potting them, growing them, ect. In order to obtain this information, three book sources, the American Orchid Society website, and one scholastic article were consulted.
Orchid BotanyOrchids are generally herbaceous or evergreen perennials. Within their family, Orchidaceae, they have common morphological structures that separated them from other plants. Their common elements are: pseudobulbs, leaves, roots, and flowers. Pseduobulbs or false bulbs, are produced by many (but not all) orchids. Those orchids that do produce pseudobulbs have one added to the rhizome each year. This rhizome creates an extending chain that may eventually divide if more than one pseudobulb is added during a given year’s growth.The pseudobulb itself contains mostly water, which allows it to conserve energy and to store moisture. It keeps the plant alive during winter—its dry and semi-dormant season.
The pseudobulb, after its leaves have been shed, is called the back bulb. They vary in shapes and sizes ranging from long thin cylinders to round or even flat structures. They can be as small as a pea or as large as a tennis ball. Although the reason for this adaptation is unknown, many times in the wild ants will live in this “cavern”. In this way, the bulb provides a home for the ants while the ants groom the orchid and keep it free from parasites and pests.
Orchids which produce pseudobulbs have a different type of leaf structure than those orchids which don’t. The sympodial orchids produce their leaves from the pseudobulb. Leaves vary in color from light green to dark grey-green and some are even speckled. Monopodial orchids produce their leaves from a single rhizome in pairs at right angles. Monopodials’ leaves are often partially rigid and flat. The wide surface is designed to catch as much light as possible.
All of the leaves contain chlorophyll, which allows the orchids to use photosynthesis to produce food. However, not all orchids have leaves. For example, the Rhizanthella species has no green growth and relies on its symbiotic fungus for nutrition.
The Chilochista species has not green foliage and contains its chlorophyll in the roots.Orchids’ roots are unique when compared to other plant types. Although there are less of them than other plant types, they are thick, white and consist of a thin inner core with an absorbent other covering consisting of dead cells. This dead layer soaks up water and is called velamen. The tips of the roots are extremely vulnerable and an be easily damaged when the orchid is outside of the soil. Although most of the roots will remain in the ground, since orchids are aerial some will come above the ground attaching to anything they find. The roots are remade annually and therefore if the roots are damaged by over watering for example, the plant will have to wait till the next growing season to right itself. While it waits, the plant will not be able to replenish its water loss as easily so the pseudobulb, if present, may shrivel and the foliage will become limp.
The flowers on orchids are widely varied per species for each plant has evolutionarily changed to allow itself to be pollinated more efficiently. Either the petals or the lip of the flower are dominant. Each flower consists of six segments—three sepals and three petals, altogether known as tepals. One of the petals is developed into a labellum or lip which is there to allow pollinating insects a place to land.Since the lip is so delicately hinged, only the right insects are able to balance and fit. The lip is also brightly colored in order to be more attractive to insects. Above the lip is the column which contains the reproductive parts of the flower. The pollen is at the end of the column in either two, four, or six masses.
The pollen is not a powder, like in other flowers, but is a grain protected beneath the anther. Beneath the column is the sticky patch where fertilization takes place.Fertilization within orchids, as previously mentioned, is accomplished by insect pollination. However, because of the many differences that have evolved within orchids—a given species may only be able to be pollinated by one insect. But since orchids are so desparate to be pollinated, they’ll sometimes accept slightly different species’ pollen and hybrid progeny results. If the hybrid produces flowers suited to a different type of insect, a new species can be born.
Plants either produce a few large seeds or many small seeds. The large seeds have a better chance of being germinated successfully, but the small seeds have a good chance of succeeding by just sheer number. Fungus also takes role in reproduction. When an orchid seed finds itself a suitable environment, it must be attacked by a specific fungus so that the seed wall will be penetrated and carbohydrates are produced.Orchid Species of SignificanceBecause of the difficulty associated with growing orchids, orchids can be rated as beginner, intermediate, and advanced.
Although there are hundreds of different types, I pulled a select few from each difficulty level in order briefly to cover the diversity of this huge family and the aesthetic pleasure of its individuals.EASY ORCHIDSBrassavolaSpecies: Bassavola nodosaLight: Very brightTemperature: Warm to intermediateWater: Will tolerate humidity levels between 30-50%, but flourishes towards the upper part of this range. They should be watered just enough to keep the tips green leaves turgid. The soil should dry completely between waterings.Potting: Cork or tree-branch mountsBrassiaSpecies: Brassia caudate, B. arcuigera, B. verrucosaLight: BrightTemperature: Intermediate to warmWater: Adapt to humidity levels between 50-70%, but prefer very wet climates.
Should be watered when the surface of the medium dries.Potting: Medium grade fir bark or tree fern mixesCattleyaSpecies: Cattleya aurantiacaLight: Bright to very brightTemperature: IntermediateWater: Humidity between 40-70%. The medium should dry completely between watering.Potting: Medium-grade fir barkCymbidiumSpecies: Cymbidium elegansLight: Bright to very brightTemperature: Warm to coolWater: Humidity between 50-70%. The medium should be watered when dry between 1-2 inches from the top.Potting: Mix should retain moisture and is porous—1 part medium grade fir bark with two parts Pro-MixEncycliaSpecies: Encyclia chocleata, E.
fragrans, E. nemoraleLight: Bright to very brightTemperature: Intermediate to warmWater: Humidity should be above 40% in winter. Medium should be watered when almost dried.Potting: Tree-fern mounts or clayOncidiumSpecies: Oncidium leucochilum, O. longipes, O. ornithorhynchum, O.
pulchellumLight: Bright to very brightTemperature: Intermediate to warmWater: Humidity should be between 40-80%, but specifically varies per species. Medium should be watered frequently especially in summer.Potting: Something that dries quickly while retaining moistureINTERMEDIATE ORCHIDSDendrobiumSpecies: Dendrobium kingianum, D. phalaenopsisLight: Low to Very BrightTemperature: Cool to WarmWater: Humidity between 80-80%. Watering varies per species.Potting: Bark, tree fern, lava, Turface, ect.LaeliaSpecies: Laelia albida, L.
anceps, L. autumnalisLight: Bright to very brightTemperature: Intermediate (to cool in winter)Water: Water only enough to keep the pseudobulbs from shriveling.Potting: Medium-grade fir barkMasdevalliaSpecies: Masdevallia floribunda, M.
infracta, M. nidificaLight: LowTemperature: Intermediate to coolWater: 75-90% humidity is optimum, but only if the air is well-circulated. The medium should never be allowed to go long without water.Potting: NZ sphagnum or sphagnum plus tree fernMiltoniaSpecies: Miltonia spectabilisLight: BrightTemperature: Intermediate to warmWater: Humidity should be around 60%.
The medium should be kept at least relatively moist.Potting: Medium-grade fir barkOdontoglossumSpecies: Hybrids like: Odontocidiums, Wilsonaras, MaclellanarasLight: Somewhat brightTemperature: Cool to intermediateWater: Humidity should approach 80%. Medium should be barely dry by the time it’s next watered.Potting: NZ moss blends and medium-grade fir barkPhragmipediumSpecies: Phragmipedium caudatum, P.
wallisiiLight: BrightTemperature: Warm to intermediateWater: Humidity should stay between 60-70%. Medium should never dry out completely and pure water should be used.Potting: Fine-grade bark or treen fern mixed with perlite and NZ sphagnumADVANCED ORCHIDSCochliodaSpecies: Choclioda roseaLight: Somewhat brightTemperature: CoolWater: Humidity should be high and between 70-100%. Medium should be kept wet all year.Potting: Tree fern, NZ sphagnum, perlite, and/or barkDraculaSpecies: Dracula erythrochaete, D.
lotax, D. velutinaLight: Low to somewhat brightTemperature: Intermediate to coolWater: Humidity should be kept between 80-100%, but the air must be well circulated. Medium should be kept saturated.Potting: NZ Sphagnum, repotted yearlyPaphiopedilumSpecies: Paphipedillum callosumi, P. hirsutissimumLight: LowTemperature: Warm to intermediate-coolWater: Humidity should be kept around 50%.
Medium should be watered when surface is dry but interior is still moist.Potting: Fine-grade fir barkSophronitisSpecies: Sophronitis cernuaLight: BrightTemperature: IntermediateWater: Humidity between 60-80% with spikes up to 100% is ideal. Medium should be watered when roots are dry.Potting: Medium-grade barkOrchid Requirements for GrowthOrchids have specific requirements which differ per species being planted. As listed in the guide, some specific mediums go with different genera of orchids.
However, there are some standard types that should be kept if growing orchids. These are: fir-bark chips, peat moss, and tree-fern fiber. If grown in a container, plastic works well because it is inexpensive and retains moisture.
In clay pots, moisture is lost more quickly however this may be considered more aesthetically pleasing. Some orchids, which grow more laterally, thrive on slabs of cork, wood, or branches (mimicking their natural habitat).Orchids may be obtained from a variety of places. They can be ordered in the mail, bought from local nurseries and greenhouses, or a present.
The orchids which are usually provided by generalized plant sellers are beginner orchids. As the level of difficulty increases, the more specialized the retailer will have to be.In order to be kept healthy, many orchids need to be repotted yearly.
This should be done right after the flowering season ends—for this begins new growth for the roots. Repotting an Orchid:1) Water the orchid.2) Remove the plant from the pot and remove all soil debris from the roots.3) Pot the plan in a container with new soil materials appropriate for its specific requirements.4) Stake the plant if necessary.
Some orchids need help to stay upright. A stake can be fashioned from wire and the orchid should be gently attached.ConclusionOrchids are extremely specialized plants and have many requirements for successful growth. Not only are their structural features different from many other types of plants, but they’re so unique that only certain insects can pollinate specific species.
In my plant list, I gave examples of aesthetically pleasing orchids grouped by how difficult it is to grow them. Finally, within my growing section, I talked more about orchid’s requirements for growth. Also, I gave a basic overview of how to repot orchids. Although orchids are more complex than many other flowers, they are accomplishable and as long as a grower begins with the proper guides (like the references I used for this paper) and with beginner’s species, they are not impossible.ReferencesCullina, William (2004). Understanding Orchids. New York, NY: Houghton Mifflin Books.
Orchid Basics . Retrieved June 3, 2008, from American Orchid Society Web site: http://www.aos.org/AM/Template.
cfm?Section=Orchid_Basics&Template=/TaggedPage/TaggedPageDisplay.cfm&TPLID=7&ContentID=3373Rittershausen, B, & Rittershausen, W (2004). The Practical Encyclopedia of Orchids: A Complete Guide to Orchids and their Cultivation.
Lanham, MD: Lorenz Books.Rogers, Marilyn (Ed.). (1999). Ortho’s All About Orchids. Des Moines, Iowa: Meredith Books.Thomas, Paul A. Growing Orchids.
Retrieved June 3, 2008, from The University of Georgia College of Agricultural ; Environmental Sciences Web site: http://pubs.caes.uga.edu/caespubs/horticulture/orchids.html
