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.

ti_kouka_sandals,jpg

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

 

close up berry-Taxus_baccata_MHNT

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

 

Peeling-Pacific-Yew-Taxus-007

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.

How the Scanning Electron Microscope works

Preparing samples for scanning electron microscope imaging

Blog post by Clodagh Dooley

Scanning electron microscopes (SEM) are amazing tools that allow imaging far beyond the resolution capabilities of light microscopes. SEMs work by creating a focused beam of electrons that scans over a sample; interacting with and exciting its atoms and generating signals that can be used to derive an image of the samples topography.

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Fig. 1.Sage leaf surface hairs. Images by Dr. Clodagh Dooley, AML, CRANN, TCD.

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Fig. 2. The scanning electron microscope used to image the Trinity Tree samples. The tool is based in The Advanced Microscopy Lab, CRANN, TCD. The microscope is a Zeiss Ultra FESEM with Gemini column and Quorum Cryo preparation chamber.

To avoid scattering of the electron beam, the electron source and the sample chamber are under vacuum. This causes no issue when working with a dry sample, such as a metal or ceramic, but can cause big problems when working with a sample with a high water content. Samples with a high water content, such as plant material, use the water as support for its structure, if this water is removed rapidly, as will happen when placed in a vacuum, then the sample will dehydrate and collapse.

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Fig. 3. The vacuum chamber of the SEM showing the loading stage.

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Fig. 4. The vacuum chamber of the SEM showing the loading stage.

The first step in preparing a biological sample for SEM is to preserve it using glutaraldehyde, a chemical fixative that prevents any breakdown and degradation of the structure. The next step is to deal with the water. This is usually done in one of two ways; removing the water in a slow, controlled manner with help of solvents or solidifying the water as ice and imaging a frozen sample.

In the first method the water in the sample is slowly replaced with alcohol by immersing it in deionised water/alcohol solutions with increasing alcohol concentration until it is in a 100% alcohol solution. The alcohol immersed sample is placed in the critical point dryer (CPD) chamber and the alcohol solution is very slowly replaced with liquid CO2. Once the alcohol within the chamber has been completely replaced with liquid CO2 the system is brought to what is termed as the ‘critical point’ for CO2. This is where the pressure and temperature within the CPD chamber causes the liquid CO2 in the sample to turn from a liquid to a gas. The gas can then be vented off without any distortion of the sample due to surface tension.

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Fig. 5. The Quorum Critical Point Dryer

The second method involves the use of liquid Nitrogen. The sample is plunged into liquid Nitrogen slush (-190°C) to flash freeze. It is then transferred, under vacuum, to a cold stage within the SEM imaging chamber where it is held at this temperatures throughout imaging. With this method of preparation, chemical fixation can be avoided as the flash freezing preserves the sample structure and prevents degradation.

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Fig. 6. Cryo preparation chamber on the side of SEM chamber.

The final step before we can image a biological/hydrated sample is to coat it with an electron conductive coating; commonly used coating materials include carbon, gold, palladium and platinum. Conductive coating prevents charging of the specimen, which is caused by accumulation of static electric fields and makes imaging difficult.

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Fig. 7. Cressington 208 Turbo sample coater.

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Fig. 8. Plant material coated in a 10nm layer of Gold Palladium.

Tree Spotlight no.6 – the Yew

pacific yew overview image

Taxus baccata is a conifer native to western, central and southern Europe, northwest Africa, northern Iran and southwest Asia. It is the tree originally known as yew, though with other related trees becoming known, it may now be known as English yew, or European yew.

yew bark image

Description: It is a small to medium-sized evergreen tree, growing 10–20 metres (33–66 ft) (exceptionally up to 28 metres (92 ft)) tall, with a trunk up to 2 metres (6 ft 7 in) (exceptionally 4 metres (13ft)) diameter. The bark is thin, scaly brown, coming off in small flakes aligned with the stem. The leaves are flat, dark green, 1–4 centimetres (0.39–1.57 in) long and 2–3 millimetres (0.079–0.118 in) broad, arranged spirally on the stem, but with the leaf bases twisted to align the leaves in two flat rows either side of the stem, except on erect leading shoots where the spiral arrangement is more obvious. The leaves are poisonous.

The seed cones are modified, each cone containing a single seed, which is 4–7 millimetres (0.16–0.28 in) long, and partly surrounded by a fleshy scale which develops into a soft, bright red berry-like structure called an aril. The aril is 8–15 millimetres (0.31–0.59 in) long and wide and open at the end. The arils mature 6 to 9 months after pollination, and with the seed contained, are eaten by thrushes, waxwings and other birds, which disperse the hard seeds undamaged in their droppings. Maturation of the arils is spread over 2 to 3 months, increasing the chances of successful seed dispersal.

Yew trees do not need rich soil but they do need a well drained site, preferably not too exposed to wind or frost. Many yews are single sex, but most Irish yews are female and so bear fruit. Even if the flesh is removed, these may be slow to germinate. The best seeds are those that have been eaten by birds and have passed through them; such bare seeds may be collected from under yew trees. The Yew tree is in fact a good tree for wildlife as birds roost and nest in it.

Longeivity: Taxus baccata can reach 400 to 600 years of age. Some specimens live longer but the age of yews is often overestimated. Ten yews in Britain are believed to predate the 10th century. The potential age of yews is impossible to determine accurately and is subject to much dispute. There is rarely any wood as old as the entire tree, while the boughs themselves often become hollow with age, making ring counts impossible. Evidence based on growth rates and archaeological work of surrounding structures suggests the oldest yews, such as the  may be in the range of 2,000 years, placing them among the oldest plants in Europe. One characteristic contributing to yew’s longevity is that it is able to split under the weight of advanced growth without succumbing to disease in the fracture, as do most other trees. Another is its ability to give rise to new epicormic and basal shoots from cut surfaces and low on its trunk, even at an old age.

fortingall-2000 year old yew

The Fortingall Yew in Perthshire, Scotland, has the largest recorded trunk girth in Britain and experts estimate it to be 2,000 to 3,000 years old, although it may be a remnant of a post-Roman Christian site and around 1,500 years old.

yew arch lo res

The Yew arch in the Golden bridge Cemetery, Dublin


In Ireland the yew is native and may be found in old woods although it is often seen in the artificial surroundings of estates or churchyards. An evergreen conifer (although an unusual one), yew is a dramatic tree with its dark foliage and red berries encasing a single seed. Reenadina wood on the Muckross Peninsula, Co. Kerry is Ireland’s only native yew wood.

yew red berries

Toxicity: All parts of a yew plant are toxic to humans with the exception of the yew berries (however, their seeds are toxic); additionally, male and monoecious yews in this genus release cytotoxic pollen, which can cause headaches, lethargy, aching joints, itching, and skin rashes; it is also a trigger for asthma. These pollen grains are only 15 microns in size, and can easily pass through most window screens.

The foliage itself remains toxic even when wilted, and toxicity increases in potency when dried. The major toxin within the yew is the alkaloid taxine. Horses have a relatively low tolerance to taxine, with a lethal dose of 200–400 mg/kg body weight; cattle, pigs, and other livestock are only slightly less vulnerable. Several studies have found taxine LD50 values under 20 mg/kg in mice and rats.

Symptoms of yew poisoning include an accelerated heart rate, muscle tremors, convulsions, collapse, difficulty breathing, circulation impairment and eventually cardiac arrest. However, there may be no symptoms, and if poisoning remains undetected death may occur within hours. Fatal poisoning in humans is very rare, usually occurring after consuming yew foliage. The leaves are more toxic than the seed.

Uses:

Wood from the yew is classified as a closed-pore softwood, similar to cedar and pine. Easy to work, yew is among the hardest of the softwoods; yet it possesses a remarkable elasticity, making it ideal for products that require springiness, such as bows. One of the world’s oldest surviving wooden artifacts is a Clactonian yew spear head, found in 1911 at Clacton-on-Sea, in Essex, UK. Known as the Clacton Spear, it is estimated to be over 400,000 years old.

Yew is also associated with Wales and England because of the longbow, an early weapon of war developed in northern Europe, and as the English longbow the basis for a medieval tactical system. The oldest surviving yew longbow was found at Rotten Bottom in Dumfries and Galloway, Scotland. It has been given a calibrated radiocarbon date of 4040 BC to 3640 BC and is on display in the National Museum of Scotland. Yew is the wood of choice for longbow making; the heartwood is always on the inside of the bow with the sapwood on the outside. This makes most efficient use of their properties as heartwood is best in compression whilst sapwood is superior in tension. However, much yew is knotty and twisted, and therefore unsuitable for bow making; most trunks do not give good staves and even in a good trunk much wood has to be discarded.

TAXUS BACCATA (YEW), TOPIARY, TREE CLOUDYew topiary tree cloud

Today European yew is widely used in landscaping and ornamental horticulture. Due to its dense, dark green, mature foliage, and its tolerance of even very severe pruning, it is used especially for formal hedges and topiary. Its relatively slow growth rate means that in such situations it needs to be clipped only once per year (in late summer).