For the creation of vertical gardens, the use of epiphytic species from the Orchid and Bromeliads families are a beautiful and practical solution. These plants are also great as indoor plants and also have terrestrial or soil based species for your outdoor garden. If you are living in a Gold Coast townhouse with a small garden, vertical gardens or green walls to hide a fences, an unsightly pillar or even a tree truck will add beauty and value to your home and help create the illusion of space. Indoor plants have been shown to improve air quality by trapping and capturing pollutants. This could also be the case with narrow outdoor spaces with vertical gardens. Recent studies have shown plants in green walls to be effective in reducing harmful nitrogen dioxide and particulate pollution in outdoor urban areas. If you are designing a landscape garden for a swimming pool a green wall, or vertical garden, might be a great way to hide the pool pump and filter and reduce noise transmission from the pump at the same time. The noise attenuation abilities of green walls could also be of benefit if you are looking to reduce the noise transmission from your neighbours or tyre and traffic noise from a nearby road. A solid wall covered in plants, placed as close as possible to the noise source will create an effective noise barrier. Where the green wall can be used to great effect for noise reduction is where there is a solid flat structure like a concrete tilt up fence or a high straight garden retaining wall. In these cases the green walls or vertical gardens can greatly reduce the echo as well has beautify.
With more than 28,000 species and nearly 1,000 genera, the orchid family must be one of the most prolific as well as the most widely spread flowers in the world. Well known for growing in the wet tropics, these colourful and fragrant plants have also colonised the tropics, sub tropic and temperate climates. Some species have even been discovered in the deserts as well as north of the arctic circle. So prolific is the Orchidaceae, as the orchid family is known, that new species are being discovered on a regular basis. Orchidaceae is a member of Asparagales, meaning that it is related to both the asparagus and another beautiful showy flower, the iris.
The name orchid comes to us via the Latin orchis from the Greek ὄρχις (orkhis) meaning testicle. This name is based on the shape of the root tuber in some species.The name avocado has a similar sense.
Terrestrial or epiphytic plants
A plant that depends on the physical support of another plant or structure is known as an epiphyte. This includes some species of ferns, many bromeliads as well some of the orchid species. For these plants, nutrients often come from rain water and debris. Recent research shows that far from being harmful to the tree, there are benefits for the host tree as well. To survive on such slim pickings, the orchid makes use of a symbiotic relationship with mycorrhizal fungi on the root system. These fungi effectively extend the root area of plants but can be disrupted by the use of the wrong fertilisers.
The ability to pull nutrients from thin air, and the fact that heavy soils or growing media are not required, make epiphytic plants ideal for the creation of vertical gardens. Whilst the majority of the tropical orchid species are epiphytes; nearly all the orchids in the temperate zones, however, are terrestrial.
Growing media for epiphytic plants in vertical gardens
For a medium to cradle the epiphytic root systems in vertical gardens, sphagnum moss is ideal. Moisten the moss and pack it against the branch. Use a bit of coconut coir around the moss to keep it contained and help retain the moisture. The coir can then be attached to the branch with hot melt glue, fishing line, twine or garden tie wire. Cut a slit in the coir and insert your plant and pack it with some extra moss. The coir can then be covered with mosses or lichens. A coir liner for a hanging basket makes a good pouch you can staple to a tree branch then fill with sphagnum moss and your orchid. Add some slits to allow the roots to grow out. Don’t be too worried if some of the root system is exposed to dappled sunlight. There is even a species of orchid that has given away using leaves for photosynthesis. The endangered Dendrophylax lindenii (Ghost Orchid) of the American everglades photosynthesizes with its roots and needs to be grown with the roots exposed.
Terrestrial Orchids for indoors.
Cymbidium orchid is a house plant that requires distinctive termperature changes between day and night to flower well.
Slipper orchids or Paphiopedilums have slipper shaped pouches to help pollination. The pollinating insect gets trapped inside the pouch. To be released the insect needs to rub against the anther. The insect then takes this pollen to the stigma of the next slipper orchid thus pollinating it. For pollinating insects there is no such thing as a free lunch.
For horticultural uses, the Vanda genus is the one most often used in the flower industry. These colourful orchids, from the family Orchidaceae, consist of about 45 species distributed from East Asia to Australia. Twelve of these species grow in Thailand. Most species have long, sturdy stems that bear closely spaced, strap-shaped leaves. By crossing species within the genus, many attractive hybrids have been developed. Some other hybrid species have been developed by crossing the Vanda species with species of other orchid genera. Colours include blood red, hot pink, blue, purple, or mottled.
Vanda flowers have spectacular colours and patterns with particularly large blooms. They are usually flat with have a short spur on the lip. The colours and patterns seen on many orchid flowers can be explained by the way pollinators are attracted to the flowers. Flowers pollinated by bees open during the day and usually have pleasant odours, bright colours a landing platform, nectar guides, (coloured lines running into the depths of the flower), as well as concealed nectaries. The basal portions of the orchid lip are usually formed into a tunnel with the column constituting its upper side. The bee enters the tunnel to get at the nectary, and as the bee backs out some of the stigmatic fluid may be rubbed on its back and carried with the bee to the next flower.
Orchids in Agriculture
One tropical climbing orchid was used by the Aztecs to flavor their chocolate beverage (xocoatl or chocolate). Later Spanish conquistador Hernán Cortés was to bring this flavor of this drink to Europe. The ingredients the Aztecs used were ground corn, cacao beans, honey and vanilla pods from the Vanilla planifolia a tropical climbing orchid. Vanilla is now commercially grown in Indonesia, the West Indies, Seychelles, and Puerto Rico. Madagascar, Mexico, French Polynesia, Réunion, and in Dominica. In the early days of the industry, little was known about how the plant was pollinated leading to very poor yields when plants were grown outside of Mexico. It was later discovered that the plant required a small Mexican bee called the Melipona bee for pollination. Interestingly, this species can also be pollinated by hummingbirds. Another vanilla species, the Tahiti vanilla, (Vanilla tahitensis) is native to Oceania.
Australian Native Orchids
With 6 new species of Drakea hammer orchids recently discovered in southern Western Australia, it is a little difficult to keep count of the exact number of orchids.
Sun Orchids are found throughout Australia as well as Indonesia, New Guinea, New Caledonia and the Philippines. Of the approximately 130 species more than 110 occur in Australia. Sun Orchids belong to the genus Thelymitra, and family Orchidaceae. The name sun orchid comes from the tendency of the flowers to only open up when exposed to strong sun light. In fact, the flowers of some self pollinating species do not open at all. The flowers have earlike appendages and the hooded column which give the genus its name of Thelymitra meaning woman’s hood in ancient Greek. In New South Wales Thelymitra ixioides is one of the most common species of Thelymitra. It can be seen growing along roadsides in NSW and southern Queensland. Despite the worldwide success of orchids, many Australian species are listed as vunerable, threatened or endangered. It is estimated that 17% of Australia’s orchids are in this category. As with the endangered Ghost orchid (Dendrophylax lindenii) of the Florida everglades, preservation of habitats and pollinators world wide is vital for wild orchids. Pterostylis tenuissima the Swamp Greenhood or Dainty Swamp Orchid is listed as vunerable and it depends upon its habitat of swamp land being protected. McIvor Spider-orchid, also known as the Audas Spider-orchid Caladenia audasii has less than 8 plants remaining in the wild.
Care of your orchids
The key to looking after your orchid is to know its original habitat and create a similar growing environment. Whilst growing some orchids can be a challenge, knowing the orchids natural habitat and recreating similar levels of light, water, temperature and growing media will help. Epiphytic orchids will not grow in soil or even potting mix. These plants require a course growing compost containing bark or sphagnum moss. Only ever use specific orchid fertilisers in the correct quantities to help maintain the health of your orchid and protect the Orchid mycorrhizas fungi. When the individual flowers droop and turn brown, carefully remove them from the flower spike. When all of the flowers from the spike are gone, cut the spike off around 30mm from the base. Once established the maintenance needs of your orchids are fairly low. Take care not to over water or over fertilise.
Bromeliads in vertical gardens.
As with the orchids, Bromelaids are either terrestrial (soil based) or epiphytic (tree based). These spectacular flowering plants number around 2600 species with nearly all of these originating in the tropics of the Americas.
Bromeliad flowers often have coloured bracts below a long spike bearing flowers with brightly contrasting sepals and petals. One species of terrestrial bromeliad is much loved by Australians and Queensland in particular. The sunshine coast of Queensland has even erected a shrine to it. The Ananas comosus or pineapple is native to tropical and subtropical America. Portuguese explorers are credited with the spread of the pineapple as an agricultural crop. It was so successful that by the start of the 1800s, it was being cultivated in most tropical areas of the world even on some remote islands of the South Pacific.
The arrangement of leaves on bromeliads including pineapples resemble that of succulents and particularly yuccas. The texture of the fruit also closely resembles pinecones giving the pineapple its name. Why would plants that are not closely related have such strong resemblance. The answer to this question comes from the field of mathematics.
Bromeliads, Pine Cones, sunflowers and other patterns in nature.
Around 1175 in Pisa Italy a boy named Leonardo was born. As his father was a customs officer, he travelled extensively around the Mediterranean and was well educated by Moorish teachers. This time in history, at the dawn of the renaissance, was when science and mathematics in particular was more advanced in the Arabic world. Leonardo of Pisa, or Fibonacci as he is better known, introduced calculation using the Hindu – Arabic numbers to the merchants of Europe thus making trade calculations much easier. Fibonacci developed his well-known sequence whilst theorizing over the maximum number of offspring a pair of rabbits could produce. As it turned out, the Fibonacci series had other application in nature that Fibonacci would not have known. It was not until the 19th century it was discovered that the Fibonacci series, where each number is the sum of the previous two, had applications in the study of botany.
So why would the plant world follow the mathematic sequence described by Fibonacci? Plants have evolved over millions of years of genetic mutation to where small advantages aid the survival of the species. For leaves this might mean capturing a little extra sunlight or rainfall. For seeds and insect hives, it means packing as much in as efficiently as possible. The result is the patterns and placements in a Fibonacci series or counter rotating spirals following the Fibonacci sequence.
For your vertical garden epiphyte plants that grow naturally on tree branches are the ideal solution. Requiring no topsoil or potting mix, the garden can be very lightweight. This is a very important consideration for some fence structures. Most often a fence will be designed and constructed without an allowance for the extra weight of potting soils. The other advantage is the epiphytes ability to capture moisture from light rainfall. In the humidity of the Gold Coast the vertical garden might only require an occasional very light spray. For the structure of vertical gardens consider using wooden trellis or lattice, recycled timber, driftwood of even recycled pallets. Some other plants to consider would be succulents, Hoya carnosa or Hoya lanceolata and philodendrons. If your vertical garden is close to your kitchen it is a great place to plant a few herbs to cook with. Many palm trees with their fibrous trunks also make ideal places to start a small vertical garden. Do not attempt this on varieties of palm trees like the canary island palm as these may be vulnerable to fungal diseases or weevils.
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