Tree spotlight no:8 – Plane Tree

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2033 year old Plan Tree in Azerbaijan

Platanus is a genus consisting of a small number of tree species native to the Northern Hemisphere. They are the sole living members of the family Platanaceae. All members of Plantus are tall, reaching 30–50 m (98–164 ft) in height. All except for P. Kerrii are deciduous, and most are found in riparian or other wetland habitats in the wild, though proving drought-tolerant in cultivation. The hybrid London plane has proved particularly tolerant of urban conditions.

They are often known in English as planes or plane trees. Some North American species are called Sycamores (especially Platanus Occidentalis), although the term sycamore also refers to the Ficus Sycomorus, the plant originally so named, and to the Sycamore maple Acer Pseudoplatanus.

london plane leaves and fruit.job

Botany:

The flowers are reduced and are borne in balls (globose heads); 3–7 hairy sepals may be fused at the base, and the petals are 3–7 and are spatulate. Male and female flowers are separate, but borne on the same plant (monoecious). The number of heads in one cluster (inflorescence) is indicative of the species (see table below). The male flower has 3–8 stamens; the female has a superior ovary with 3–7 carpels. Plane trees are wind-pollinated. Male flower-heads fall off after shedding their pollen.

After being pollinated, the female flowers become achenes that form an aggregate ball. Typically, the core of the ball is 1 cm in diameter and is covered with a net of mesh 1 mm, which can be peeled off. The ball is 2.5–4 cm in diameter and contains several hundred achenes, each of which has a single seed and is conical, with the point attached downward to the net at the surface of the ball. There is also a tuft of many thin stiff yellow-green bristle fibers attached to the base of each achene. These bristles help in wind dispersion of the fruits as in the dandelion.

plane tree seed head

The leaves are simple and alternate. The mature bark peels off or exfoliates easily in irregularly shaped patches, producing a mottled, scaly appearance. On old trunks, bark may not flake off, but thickens and cracks instead.

Uses

The principal use of these trees is as ornamental trees, especially in urban areas and by roadsides. The London plane is particularly popular for this purpose. The American plane is cultivated sometimes for timber and investigations have been made into its use as a biomass crop. The oriental plane is widely used as an ornamental and also has a number of minor medicinal uses.

Cultural history

Most significant aspects of cultural history apply to Platanus orientalis in the Old World. The tree is an important part of the literary scenery of Plato’s dialogue Phaedrus. Because of Plato, the tree also played an important role in the scenery of Cicero’s De Oratore.

Behind the art works – the Cordyline Palm

cordyline-australis

Before the team and I decided on which trees to include in our project we visited the various trees on the Trinity College campus. Personally I was drawn time and time again to the mesmerising swaying of the flexible tree branches and the soft meditative swishing sound created by the wind rustling through the leaves of the Cordyline Palm. In the end we decided to include the palm tree with it’s multiple branches growing closely together from the base as a counterpoint to the size and stocky nature of the other trees, which have a single trunk and many branches. I knew from very early on that any artwork I would make would have to reference the delicate appearance of this tree while also referencing it’s very specific physiology.

As I thought further and researched more about the palm tree I was reminded of a two week holiday I took in Bali over ten years ago. Each day I encountered numerous offerings left outside houses, on pathways and in the temples by the locals. Each parcel was simple yet beautiful created using banana or palm leaves and filled with rice and colourful flowers.  See images above.

More importantly I was very lucky to be in Bali around the time of the Galungan festival. Galungan marks the beginning of the most important recurring religious ceremonies in Bali. The spirits of deceased relatives who have died and been cremated return to visit their former homes, and the current inhabitants have a responsibility to be hospitable through prayers and offerings. The most obvious sign of the celebrations are the Penjor – bamboo poles with offerings suspended at the end. Every street is lined with Penjors outside each house one more decorative than the next.

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The main material needed to make a Penjor is a long, curved bamboo pole. The pole is then decorated with coconut leaves and various other natural items. At the end of each Penjor a decorative Sampian is hung made with coconut or palm leaves and flowers.

I remember at the time being captivated by the amazing diversity of shape and texture the Balinese could create with such a simple materials.

For the Trinity College Trees project I decided to create a Penjor of sorts to represent the Cordyline palm. Its strength and flexibility alongside it’s delicate appearance is the perfect vessel to embody the nature of this tree.

When I made this initial decision a few months ago I collected a large black bin bag full of fallen Cordyline Palm leaves from Trinity College. I worked with the leaves, curving and shaping them over a few weeks. The colour of the leaves for me was an issue, the natural brown didn’t really fit with the chosen colour aesthetic. I tried painting the leaves with bright neon acrylic paints but the result looked forced.

I abandoned the palm leaves and decided to cover the curved bamboo pole with neon orange ribbon and create my own decorative elements with an electric blue fabric.

The shapes of these elements were chosen based on some of the SEM images of the internal cellular structure of the Palm. David Hackett kindly explained that the Cordyline Palm is a monocot. This didn’t mean much to me initially but now I understand it that a monocot, as the name suggests, has one ‘cot’ or cotyledon. A cotyledon is basically the first leaf that sprouts from a seed. Monocots have one, and dicots have two. Basically some plants have one leaf to start their lives out with, and some have a pair.

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left: monocot, right: dicot

The reason I mention this is that I was interested in how the cellular structure of the Palm (as a monocot) looked and differed functionally to all the other trees in the project, which are dicots. As you can see in the SEM image below of a cross section of the parallel veins of the palm they are laid out in bundles, which are then arranged together to create the internal cellular structure of the branch.

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I used the various shapes from these bundles to create the decorative elements of the Penjor. Imagery from the cross section of the veins in the bundles were recreated by drawing in neon orange acrylic paint on the blue fabric sections. Finally I will draw on imagery of the breathing hole (soma) from the underside of the palm leaf while creating the decorative Sampian at the end of the bamboo pole.  See images below of the work completed on the Penjor to date.  I will post updated images of the work at a later stage. 

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The art works in progress – Hop Hornbeam

Before undertaking the making of the artwork for the Hop Hornbeam tree I had to figure out how to make it. I could not work directly on the tree while shaping and making the ‘corset’. I also realised that it would be virtually impossible to measure accurately all the curves and bends of the 3D shape. I would therefore need to create a rough mould to work with and on. Normally I would have done this using plaster bandage/ silicone etc, materials that were definitely not suitable for working with a crumbly bark surface. After some thought and a chat with my fellow artist and super mould maker Ayelet Lalor we decided that the malleable and un intrusive properties of tinfoil would work best.

So one fine morning about a month ago Ayelet, Clodagh Dooley and I set about making a temporary tinfoil mould of the selected area. We used copious amounts of tinfoil, selotape and support sticks. See image below of Clodagh and Ayelet busy helping me with the large task. Thanks again to both of them. It was quite a fun task to do and of course we got some interesting looks and comments from passers by.

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As the piece to be moulded was so large we created it in three more manageable sections, which I transferred by car to my studio. I quickly backed the reverse of the mould with plaster bandage to preserve the shape and add strength. See image below.

backing of Mould of Hophornbeam lo res

The next step in the process was somehow to get the mould into a similar set up to the real life tree in my studio. Using a mannequin as a central support and substructure I covered it with chicken to roughly simulate the tree trunk. The mould was gently re-attached and adhered to the substructure.  I set to work trying out various ideas on how I would segment the artwork. See images below.

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After deciding which option to go for I made paper patterns for the corset. This was a quite a tricky process as you can see bellow.

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Finally I placed the pattern sections on the fabric and cut out the individual pieces. Each section was then carefully sewn together. See images below.

The time had come to see how the artwork looked and functioned. I pegged the work onto the mould. At this stage I lightly stuck on some of the blue fabric strips onto the lines delineating the different sections. See images below.

Happy with the progress of the piece so far I now had to remove the blue strips and sew an extra channel into each section to allow the support wire to be inserted. At this stage I felt it was important to bring the piece into Trinity to test it’s fit. Before doing this I reattached the piece to the mould to work out some of the kinks with the wiring and fit before doing this.

On a Saturday the 24th of June I brought the work in progress into Trinity and spent many hours stretching and temporarily tying it into place. It was during this time that I had to make some final decisions on where the tying points should be on the corset. Seeing the piece in place also helped me decide on the need to wire and cover all the edges of the corset with the blue fabric. See a selection of images from the installation.

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Lots more work needs to be done to the surface of the corset. I won’t post any more images of it until it has been finally installed in late September 2017.

The exhibition will officially open to the public on Friday 29th of September. The opening will coincide with the Trinity College European Researchers Night 2017 events. During the evening Olivia Hassett will perform alongside the Oregon Maple in the main square twice and there will be also be a guided walk of the eight artworks spread throughout the Trinity College Campus. I will post the eventbrite details to sign up for the guided walk at a later stage.

Behind the art works – the Hop Hornbeam

When researching and developing the artwork for the Hop-hornbeam (Ostrya) I was drawn initially to meaning behind it’s names. The name Ostrya is derived from the Greek word ostrua, “bone-like”, referring to its very hard wood. It is also called Ironwood. These thoughts led me to revisit my collaboration with David Taylor on our exoskeleton project and subsequent two person exhibition in the Parsons Building, Trinity College Dublin in September 2015.

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The trajectory of my own practice since then has included the creation of sculptural elements that took on some of the physical and technical properties of abstracted corsets as exoskeletons.

Images above show the protuberance that I am interested in

The physiology of the tree was also a source of inspiration in particular the lumpy shaped protuberance that snaked around the outside of the tree. It was really interesting to hear from David Hackett that this growth is a direct result of the tree’s reaction to wind factors and it’s environment in general.

My favourite SEM imagery taken from this tree was the microscopic spiky thorn-like structures that were growing on the surface of the branches.   See image below taken by Clodagh Dooley.  Thanks to Daniel Kelly and John Parnell of the TCD Botany Department I now know that they are epidermal hairs, which are only visible on the very young twigs of the Hop Hornbeam.

Hop Horn Beam004 lo res

All these thoughts and inspirations have led me to the decision to create a corset-like protective covering for the large protruding element snaking around the lower trunk. The artwork will be made from bright orange heavy swimsuit-like fabric, cut into various segments and sewn together using corset making techniques. Where normal corsets add boning (a plastic/metal strip inserted into channels sewn in the corset to create of to create structure) I will insert wire between each segment. This will allow the artwork to follow the natural lumps and hollows of the bark. Finally these lines will be accentuated by the addition of electric blue sticky fabric strips and spikes reminiscent of the SEM imagery.

Tree spotlight no:7 – Cordyline Palm

cordyline-australis

Cordyline australis, commonly known as the cabbage tree, cabbage-palm is a widely branched monocot tree endemic to New Zealand. The genus name Cordylinem derives from an Ancient Greek word for a club (kordyle), a reference to the enlarged underground stems or rhizomes, while the species name australis is Latin for “southern”. The common name cabbage tree is attributed by some sources to early settlers having used the young leaves as a substitute for cabbage.

It grows up to 20 metres (66 feet) tall with a stout trunk and sword-like leaves, which are clustered at the tips of the branches and can be up to 1 metre (3.3 feet) long. With its tall, straight trunk and dense, rounded heads, C. Australis is a characteristic feature of the New Zealand landscape. Its fruit is a favourite food source for the New Zealand pigeon and other native birds.

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It grows in a broad range of habitats, including forest margins, river banks and open places, and is abundant near swamps. The largest known tree with a single trunk is growing at Pakawau, Golden Bay. It is estimated to be 400 or 500 years old, and stands 17 metres (56 feet) tall with a circumference of 9 metres (30 feet) at the base. Known to Māori as tī kōuka, the tree was used as a source of food, particularly in the South Island, where it was cultivated in areas where other crops would not grow. It provided durable fibre for textiles, anchor ropes, fishing lines, baskets, waterproof rain capes and cloaks, and sandals.

Hardy and fast growing, C. Australis is widely planted in New Zealand gardens, parks and streets, and numerous cultivars are available. The tree can also be found in large numbers in island restoration projects such as Tiritiri Matangi Island, where it was among the first seedling trees to be planted.

It is also grown as an ornamental tree in Northern Hemisphere countries with mild maritime climates, including parts of the upper West Coast of the United States and the warmer parts of the British Isles, where its common names include Torbay palm, and Torquay palm. It does not do well in hot tropical climates like Queensland, Southeast Asia and Florida.

Magnified view of flowers of C. australis. Each flower has a style tipped by a short trifid stigma. There are also anthers with pollen, and nectar around the base of the ovary. In a good flowering season, a large tree may produce 1 million seeds. Before it flowers, it has a slender unbranched stem. The first flowers typically appear at 6 to 10 years old, in spring. After the first flowering, it divides to form a much-branched crown with tufts of leaves at the tips of the branches. Each branch may fork after producing a flowering stem. The pale to dark grey bark is corky, persistent and fissured, and feels spongy to the touch.

The long narrow leaves are sword-shaped, erect, dark to light green, 40 to 100 cm (16 to 39 in) long and 3 to 7 cm (1.2 to 2.8 in) wide at the base, with numerous parallel veins. The leaves grow in crowded clusters at the ends of the branches, and may droop slightly at the tips and bend down from the bases when old. They are thick and have an indistinct midrib. The fine nerves are more or less equal and parallel. The upper and lower leaf surfaces are similar.

Large, peg-like rhizomes, covered with soft, purplish bark, up to 3 metres (9.8 feet) long in old plants, grow vertically down beneath the ground. They serve to anchor the plant and to store fructose in the form of fructan. When young, the rhizomes are mostly fleshy and are made up of thin-walled storage cells. They grow from a layer called the secondary thickening meristem.

Response to fire

Cordyline australis is one of the few New Zealand forest trees that can recover from fire. It can renew its trunk from buds on the protected rhizomes under the ground. This gives the tree an advantage because it can regenerate itself quickly and the fire has eliminated competing plants. Cabbage tree leaves contain oils which make them burn readily. The same oils may also slow down the decay of fallen leaves, so that they build up a dense mat that prevents the seeds of other plants from germinating. When the leaves do break down, they form a fertile soil around the tree. Cabbage tree seed also has a store of oil, which means it remains viable for several years. When a bushfire has cleared the land of vegetation, cabbage tree seeds germinate in great numbers to make the most of the light and space opened up by the flames.

Insect habitation:

Insects, including beetles, moths, wasps and flies, use the bark, leaves and flowers of the tree in various ways. Some feed or hide camouflaged in the skirt of dead leaves, a favorite dry place for weta to hide in winter. Many of the insect companions of C. Australis have followed it into the domesticated surroundings of parks and home gardens. If the leaves are left to decay, the soil underneath cabbage trees becomes a black humus that supports a rich array of amphipods, earthworms and millipedes.

There are nine species of insect only found on C.australis, of which the best known is Epiphryne verriculata, the cabbage tree moth, which is perfectly adapted to hide on a dead leaf. Its caterpillars eat large holes and wedges in the leaves. The moth lays its eggs at the base of the central spike of unopened leaves. The caterpillars eat holes in the surface of the leaves and leave characteristic notches in the leaf margins. They can infest young trees but seldom damage older trees, which lack the skirt of dead leaves where the parent moths like to hide.

The Cordyline Palm and the Māori:

The tree was well known to Māori before its scientific discovery. The generic Māori language term for plants in the Cordylinegenus is tī, and names recorded as specific to C. Australis include tī kōuka, tī kāuka, tī rākau, tī awe, tī pua, and tī whanake. Each tribe had names for the tree depending on its local uses and characteristics. Simpson reports that the names highlight the characteristics of the tree that were important to Māori. These include what the plant looked like—whether it was a large tree (tī rākau, tī pua), the whiteness of its flowers (tī puatea), whether its leaves were broad (tī wharanui), twisted along the edges (tī tahanui), or spiky (tī tarariki). Other names refer to its uses—whether its fruit attracted birds (tī manu), or the leaves were particularly suitable for making ropes (tī whanake) and nets (tī kupenga). The most widely used name, tī kōuka, refers to the use of the leaf hearts as food.

cordyline_berries

The berries of C. Australis are enjoyed by bellbirds, tūī and pigeons. Māori sometimes planted groves of cabbage trees (pā tī) to attract pigeons which could be snared when they came to eat the berries.

Food

The stems and fleshy rhizomes of C.australis are high in natural sugars and were steam-cooked in earth ovens (umu tī, a large type of hāngi) to produce kāuru, a carbohydrate-rich food used to sweeten other foods. The growing tips or leaf hearts were stripped of leaves and eaten raw or cooked as a vegetable, when they were called kōuka—the origin of the Māori name of the tree.

Preparation of a modern hangi for tourists at Mitai Maori Village, Rotorua

The kōata, the growing tip of the plant, was eaten raw as medicine. When cooked, it was called the kōuka. If the spike of unopened leaves and a few outer leaves is gripped firmly at the base and bent, it will snap off. The leaves can be removed, and what remains is like a small artichoke heart that can be steamed, roasted or boiled to make kōuka, a bitter vegetable available at any time of the year. Kōuka is delicious as a relish with fatty foods like eel, mutton birds, or pigeons, or in modern times, pork, mutton and beef. Different trees were selected for their degree of bitterness, which should be strong for medicinal use, but less so when used as a vegetable.

palm as fibre plant for weaving

Fibre

A tough fibre was extracted from the leaves of C.australis, and was valued for its strength and durability especially in seawater. The leaves were used for making anchor ropes and fishing lines, cooking mats, baskets, sandals and leggings for protection when travelling in the South Island high country, home of the prickly spear grasses (Aciphylla) and tūmatakuru or matagouri (Discaria toumatou). Morere swings provided a source of amusement for Māori children. The ropes had to be strong, so they were often made from the leaves or fibre of C.australis, which were much tougher than the fibers of New Zealand flax. The leaves were also used for rain capes, although the mountain cabbage tree C.indivisa, was preferred. The fiber made from cabbage tree leaves is stronger than that made from New Zealand flax.

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Medicine

The Māori used various parts of Cordyline australis to treat injuries and illnesses, either boiled up into a drink or pounded into a paste. The kōata, the growing tip of the plant, was eaten raw as a blood tonic or cleanser. Juice from the leaves was used for cuts, cracks and sores. An infusion of the leaves was taken internally for diarrhea and used externally for bathing cuts. The leaves were rubbed until soft and applied either directly or as an ointment to cuts, skin cracks and cracked or sore hands. The young shoot was eaten by nursing mothers and given to children for colic. The liquid from boiled shoots was taken for other stomach pains. The seeds of Cordyline australis are high in linoleic acid, one of the essential fatty acids.

Yew the sacred and the mystical

 

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The evergreen yew with dark green, needle-like leaves and red berries has commonly symbolized immortality in the Indo-European imagination as it is the longest-lived entity, often lasting more than 1,000 years, to be found in the European environment.

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Yew tree believed to be more than 1,000 years old in the churchyard of St Peter & Paul Harlington, near Heathrow Airport

The yew tree has been found near chapels, churches and cemeteries since ancient times as a symbol of the transcendence of death, and is usually found in the main squares of the villages where people celebrated the open councils that served as a way of general assembly to rule the village affairs. It has been suggested that the Sacred Tree at the Temple at Uppsala was an ancient yew tree.

The Christian church commonly found it expedient to take over existing pre-Christian sacred sites for churches. It has also been suggested that yews were planted at religious sites as their long life was suggestive of eternity, or because being toxic they were seen as trees of death. Another suggested explanation is that yews were planted to discourage farmers and drovers from letting animals wander onto the burial grounds, the poisonous foliage being the disincentive. A further possible reason is that fronds and branches of yew were often used as a substitute for palms on Palm Sunday. It is still commonly planted in Christian churchyards and cemeteries.

Conifers were in the past often seen as sacred, because they never lose their green. In addition, the tree of life was not only an object from the stories, but also believers often gathered around an existing tree. The yew releases gaseous toxins (taxine) on hot days. Taxine is in some instances capable of causing hallucinations. This has some similarities with the story that Odin had a revelation (the wisdom of the runes) after having been hanging from the tree for nine days.

druids yew wand

The druids preferred yew for wand-making over their other favourite woods, apple and oak. Several Irish and Scottish place-names allude to the yew, notably Youghall [Eochaill, yew wood] in County Cork. The Irish personal name Eógan means ‘born of the yew’, so that the great Munster dynasty could be glossed as ‘people of the yew’.

Yew and Chemotherapy drug Taxol

 

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Certain compounds found in the bark of yew trees were discovered by Wall and Wani in 1967 to have efficacy as anti-cancer agents. The precursors of the chemotherapy drug paclitaxel (taxol) was later shown to be synthesized easily from extracts of the leaves of European yew, which is a much more renewable source than the bark of the Pacific yew (Taxus brevifolia) from which they were initially isolated. This ended a point of conflict in the early 1990s; many environmentalists, including Al Gore, had opposed the destructive harvesting of Pacific yew for paclitaxel cancer treatments. Docetaxel can then be obtained by semi-synthetic conversion from the precursors.

Paclitaxel chemotherapy drug from yew

Paclitaxel is in the taxane family of medications. (PTX), sold under the brand name Taxol among others, is a chemotherapy medication used to treat a number of types of cancer. This includes ovarian cancer, breast cancer, lung cancer, Kaposi sarcoma, cervical cancer and panc cancer. It works by interference with the normal function of microtubules during cell division. It is given by injection into a vein. There is also an albumin bound formulation.

Paclitaxel was first isolated in 1971 from the Pacific Yew and approved for medical use in 1993. It is on the World Health Organisation’s List of Essential Medicines, the most effective and safe medicines needed in a health system. The wholesale cost in the developing world is about 7.06 to 13.48 USD per 100 mg vial. This amount in the United Kingdom costs the NHS about 66.85 pounds. It is now manufactured by cell culture.