TISA (Taxus baccata)
Grm ali do 15 m visoko zimzeleno drevo; 3.-4.

Uspeva v vlažnih, senčnih predeli bukovih in mešanih gozdov montanskega pasu. V naravi je razmeroma redka (Notranjska, Kozjansko, Pohorje, Kozjak), pogosteje je gojena (Pohorje, Zg. Savinjska dolina).

Zavarovana je od l.1976. Zaradi počasne rasti je tisin les zelo kakovosten in iskan.

Semena vsebujejo 16% sladkorja, 0,5% pektina, 1,7% proteina in nekaj mineralnih snovi in organskih kislin.

Tisino drevo je žilavo in odporno in se uporablja za rezbarjenje in za izdelavo različnih predmetov.

To je morda eden od vzrokov da je jo je kot samonikle rastline vse manj v svetu.

Tisa uspeva na vseh kontinentih razen v Avstraliji.

Baccatin III [CAS RN:27548-93-2]

Synonyms:

C₃₁H₄₀O₁₀

572.651

ACX: X1000646-7

Taxus Baccata ‘Fastigiata’

1968 Irish Yew. It is a very upright variety of the common English Yew. In this kind there are no flat lateral branches, as is usual with yews. Caution: the berry-like aril surrounding the mature seed of the Irish Yew is edible, but the seed itself is very poisonous. 

It was originally found by a farmer in Fermanagh in 1780. After the Earl of Enniskillen made cuttings available to nurserymen in 1867, it has been much propagated vegetatively.

Tree of Life, the YEW

Pacific Yew produces taxol a derivative from the bark and leaves that is used in treating ovarian cancer. Pacific yew also know as western yew (Taxus brevifolia) is a small tree found on the west coast from the southern pan handle of Alaska through northern California. It tolerates very low light conditions, consequently it is found scattered in the forest under many taller trees like Douglas-fir and western red cedar. The leaves are narrow, needle-like and evergreen. Photo: Yew branch with berry. Only the female tree (it is dioecious, having both male and female trees separately) produces a most interesting fruit called an aril, which is a bright red fleshy berry-like structure with part of the seed exposed at one end. This attractive, but poisonous fruit, attracts birds which easily disperse the seed, complete with bird fertilizer in the forest. The tree doesn't get much over 35 feet in height and is often very scraggly looking. I like to refer to it as the "old hag" of the forest! But it's really a wonderful tree with many uses including modern medicine.

Northwest native Americans utilized this tree for many purposes, according to tribal folklore (Gunther, 1973). The wood is very pliable without breaking consequently many bows and arrows were crafted. The Makah Indians made their whaling harpoons from larger yew stems. Canoe paddles, clubs, spoons, and combs were other uses of the wood. The Chehalis would bath a baby or older person in the steeped leaves mixed in water for making them feel better. The Cowlitz moistened the leaves, ground them up, and applied this to wounds. The Quinalt would go a step further by chewing the leaves and then spitting them on wounds. The Quinalt were also the only tribe recorded to have used the bark for medicine, specifically lung medicine.

The English yew is partly responsible for bringing an end to the Middle Ages when in 1415 its wood used for longbows that were superior to armored calvary. The Battle of Agincourt was won and the age of chivalry began. The same English yew is being grown today by the Weyerhaeuser Company in Washington for taxol compounds used for treatment of ovarian cancer.

In 1966 a botanist in Oregon supplied leaves, bark and twigs to the National Institute of Health (NIH) in Maryland where thousands of plants were being tested for cancer treatment. The sample of bark from the yew was most active against the laboratory cancer cells. It arrested tumor growth. Chemists isolated an ingrediant now refered to as taxol. Clinical trials of its effectiveness began with serious interest in 1983 when it again showed promise. Then in 1989, medical researchers at Johns Hopkins reported that 12 women with advanced levels of ovarian cancer who had not responded to any other treatment, had a 50% or more decrease in the size of their tumors. One woman's tumor disappeared altogether. Today taxol is registered by the FDA as an official treatment for ovarian cancer. However it requires the bark of about 3 to 4 yew trees to treat one person for a year. And the yew is uncommon. Consequently the mass production of young trees in the Weyerhaeuser nursery, and the race to develop a partial synthetic replica of taxol in the laboratory.

Laboratories in England, Holland, and France are researching synthesis of the anticancer drug taxol with the foliage of yew that grows in Europe. An interesting tie to the English garden exists in the production of this product. The laboratories in England collect yew leaves from the trimmings of the world's largest maze, like a rat maze, but made for humans in the garden out of yew hedges found at Longleat House, Wiltshire, England. Another important dependency on plants for both adornment, the garden, and health, the medical treatment. Surely yew is to be regarded as the "tree of life" as it was in ancient mythology.

For more information check out the Yew Page.

Measuring photosynthesis in the field

Knowing the physiological tolerance of a species to changes in its environment is critical to successful management. At the start of our research, very little was known about the range of conditions under which Pacific yew can survive and grow, so a considerable part of our program was devoted to defining the tolerance limits of Pacific yew.

A wide variety of foliage, structural, and functional measurements were taken including; photosynthetic rate (based on the amount of C0₂ uptake per given leaf area in a given time), incoming light levels, temperature, soil moisture, xylem water potential (a measure of water stress in the foliage), and chlorophyll fluorescence (a measure of the plant's capacity to efficiently utilize light). Structural characteristics of the foliage such as specific leaf area (square centimeters of area covered by one gram of needles) were also determined as well as % nitrogen and chlorophyll content.

Results

Sex

We found no differences in foliar physiology or morphology between male and female Pacific yew. This would indicate that male and female trees have equal capacities to tolerate stresses and to grow in understorey or open (full sun) environments.

Light

Yew seedling growing in open clearcut

The capacity of Pacific yew foliage to tolerate shade and exposure to full sun was investigated. Photosynthesis (C0₂ uptake) and transpiration (the amount of moisture passing out of the leaf) were similar whether the shoot was grown in sun or shade. In addition, photosynthetic responses to light and maximum photosynthetic rates did not differ between foliage grown in sun or shade. Water use efficiency (water loss per unit of C0₂ taken up) was not different between sun and shade foliage.

The two types of foliage did differ in structure and efficiency of light use. Shade grown Pacific yew produced longer, wider and thinner leaves with greater capacities to capture and use light than trees grown in sun.

Yew foliage will take on a bronze colour in response to high light

Potential for water loss was measured from electron micrographs of stomatal (pores in the leaf surface which control water loss) number and distribution. Sun foliage had more stomata per square centimeter but individual leaves had equal numbers of stomata compared with shade foliage. This would indicate equal water loss potential in sun and shade leaves.

The foliage of Pacific yew also has the capacity to produce pigments which apparently act to protect the foliage from high levels of sunlight. These pigments tend to give the foliage a bronzed colour. We have observed low temperature and poor nutrition can increase bronzing, so high levels of these pigments may indicate stress in the trees.

Ecological Significance

By altering leaf form and function, Pacific yew can survive and grow in a wide variety of light environments. The capacity to adjust to sun and shade gives Pacific yew the potential to establish itself with other pioneer species in disturbed areas and remain viable as faster growing trees over-top them. We have observed yew seedlings growing both in clearcuts and in very deep shade (5% of full sun) in the forest understorey.

Measuring light use efficiency

Water

Although Pacific yew has hitherto been thought intolerant of water stress because it was found primarily in valley bottoms and riparian (stream side) environments, we have found it in very dry ecosystems that have profound seasonal water deficits. During the course of three years of monthly measurements of foliar physiology in natural stands, we have found that, despite very low light levels (10 % of full sun) and water stress (5% soil water content), yew foliage could maintain a positive carbon balance (more C0₂ taken in than lost) more than 95% of the time. This capacity to efficiently capture and use light, water and nutrients underlies the wide distribution of Pacific yew in British Columbia.

Environmental Debate

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An environmental debate arises concerning the Pacific Yew and the extraction of Taxol. Pacific Yews grow in the old-growth forests. Douglas Firs also grow in those forests. Therefore, loggers needing the Firs cut down the Pacific Yew along with the Firs. The Yew trees are then burnt. Since these Yew trees do not resist fire well, they cannot be salvaged. As a result, an estimated ninety percent of the trees have been cut down. In addition, the Yew grows extremely slow. They cannot replace themselves quickly enough to survive the timber companies chopping them down.
A possible explanation for the logging problem could be to simply not cut down the Yew trees. However, the Yew trees do not handle excess sunlight very well. They cannot survive and grow without an abundance of shade.
Yews cannot be grown either. They would not survive in a Conifer plantation because their reproduction is through their berry-like seeds. These seeds are not simply blown away though. They, theoretically, are carried by the birds. Thus, the growth of the Yew trees could not be controlled.
Both researchers and environmentalists have a need for the survival of the Pacific Yew. The environmentalists see the Pacific Yew as a threatened species. They also want the protection of the old-growth forests in which the Yew grows.
The researchers and scientists see importance in the Yew tree for its compound, Taxol. The company, Bristol-Meyers Squibb is especially interested in producing taxol for cancer patients. Bristol-Meyers Squibb, however, needs about 170,000 punds of taxol for their research per year. Unfortunately this would destroy 35,00 to 40,000 trees per year. As a result, if the Taxol could be used and studied at this extent, it would take 6 to 8 trees to medicate one person with Taxol. Therefore the environmentalists are "fighting" Bristol-Meyers Squibb for the survival of the tree.
In a comprimise, the Department of Agriculture has granted Bristol-Meyers Squibb the right to harvest the Yew but only in exchange for sponsoring some sort of ecological research on the tree. The environmentalists are still not pleased though. They see the importance of the Taxol but they do not believe all the trees should be cut down. The feel there is no clear plan by Bristol-Meyers Squibb on how to maintain the Yews. As well, the company has a monopoly over the harvesting methods. Therefore, other companies are prevented from working on "renewable extraction methods" and from having access to the trees. The Forestry Service feels that an alternative method for extracting the Taxol trees will be discovered in the next four years. Thus, they think the trees would be fine to be chopped down now.
Regardless, both the environmentalists and the researchers want to preserve the Yew. The conservationists and cancer researchers have, as a result, pushed and gotten the U.S to list the Pacific Yew as "threatened" under the Endangered Species Act. However, the Bristol-Meyers Squibb manages the National Cancer Institute's supply of taxol and organizes more of the clinical trials. This costs $200,000 per kilo and asa result, is potentially very valuable to companies. Unfortunately, it takes 9000 kilos of bark to make only 1 kilo of Taxol. Therefore, a new method of producing Taxol without exterminating the tree is needed. Thus, the medical demand for the tree could actually save the Pacific Yew tree.

Hills Creek is a small reservoir just past Oakridge, largely surrounded by young tree plantations. The vegetation here is much like that of our next stop, Shady Beach, before it burned. At this stop we mostly covered some common Cascade forest organisms such as Poison Oak Rhus diversiloba, Pacific Madrone Arbutus menzeisii, Big leaf maple Acer macrophyllum, and Pacific Yew Taxus brevifolia.

The Pacific Yew, Taxus brevifolia, are found from sourthern Alaska to northern California. They are commonly found as an under story tree in Pacific coast forests, growing in similar areas as western hemlock. The leaves range from one and one-half to one inches long. The bark is a thick dark purplish or red-brown color: flaky or scaly. Pacific Yew has a long reddish, oval fruit that is 2/8-5/8 inches. It's been called the most promising new cancer drug to come along in years. Taxol, extracted from the bark of Pacific Yew, has been shown to be effective against ovarian cancer and may assist in the treatment of other forms of the disease.

Poisin Oak, Rhus diversiloba, is usually an erect shrub, but in low light it will climb and use aerial rootlets. It has oak-shaped toothed leaflets in groups of three. Its color is a light shiny green to dark green to bright red depending on the time of year. Small green flowers occur in leaf axils. The poisonous fruits are small white or cream colored berries which hang in clusters. Environmental conditions often result large variations in plant form from one locale to another.

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Other Organisms at Hills Creek:

Pacific Madrone

Big Leaf Maple

Pacific yew [also referred to as Western yew] Taxus brevifolia Nutt.

The following text is from The Tree Book: Learning to Recognize Trees of British Columbia
a joint publication of the Canadian Forest Service and the British Columbia Ministry of Forests

Pacific yew

A low spreading shrub to a small tree, 5 to 15 metres tall; young trees are often square in profile,becoming more cone-shaped with age. The trunk is twisted and becomes very wide near the base, with horizontally spreading branches.

The photograph to the left shows a Pacific yew growing in full sun in a Victoria area industrial park.

Leaves

Needles are flat, about 2 centimetres long, with a distinctive pointed tip; dark yellowish-green, arranged spirally on twigs but twisted so that they appear to grow in two rows.

Cones and Fruit

Seed (left) and pollen cones (right) usually appear on separate male and female trees.

The fruit consists of a coral-red fleshy cup that is open at one end and contains a single seed.

Bark

Thin, dark reddish or purplish scales shed from the trunk and expose a rose-coloured underbark.

Where to find Pacific yew

It occurs scattered throughout the wetter forests of the coast and the Interior wet belt, primarily at low to mid elevations.

Distribution is shown in darker colours in the map to the right.

Habitat

Pacific yew occurs on a wide variety of sites, from dry and rocky to moist depressions and ravines; it generally occurs on sites that have abundant soil nutrients. It often occurs together with Douglas-fir, western redcedar, and western hemlock, as well as plants such as salal, Oregon-grape, or skunk cabbage. Where it does occur, it is important food for black-tailed deer, elk, moose, and caribou.

Several birds - including blackbirds, waxwings and nuthatches - and various small rodents eat the fruit. In so doing, they scatter the seed away from the tree.

Uses

Although the fruit of western yew is considered toxic, some coastal native groups occasionally ate it in small amounts.

The native people used the strong, stiff wood for making items such as bows, tools, paddles,and prying sticks. It is still used for making bows and paddles. Interior peoples sometimes used the branches to make snowshoe frames.

The adjacent drawing shows a native halibut hook made from yew.

The bark of western yew contains a compound called taxol, which shows promise in treating some forms of cancer.

Notes
Taxus is a Latin word for "bow." Some historians believe that Robin Hood's bow was made from English yew.

index current projects cabinets | tables | chairs | desks who | where | how notes

Species	Solid	Veneer	Grain	Uses
Yew	+	++	fine close texture curly irregular grain	Furniture, Decorative panels, Musical Instruments

timber resource

Notes :

Wood is an Organic material, and is liable to strong variations of colour & grain depending local conditions during a trees life.

The samples & descriptions shown below are therefore representative samples only.

Scans were taken from lacquered veneer samples and variations can & do occur between solid timber & veneer stocks.

We strongly recommend requesting hand samples from a local supplier prior to specification.

Availability of species will vary from place to place and specifications below are based on our local conditions. However veneers can be parcelled & despatched via ordinary post succesfully.

Rating explanation

+++ = excellent
++ = good
+ = poor

Grain describes both physical (texture) & visual (grain) characteristcs

Uses is an indication of the most common occurrences, and does not attempt to suggest limitations of use.

The Chalice Well, Glastonbury

Vesica Yew

This Vesica is not only sacred to Christians. It is an important symbol for many spiritual paths. Just up the hill from the Vesica Pool, on the right next to a door in the wall, is an old yew tree that has grown apart at the base and then grown together again about six feet higher up. This vulvic shape is sacred to the Goddess,and many visitors see these waters as Her blood spring.

King Arthur's Courtyard The next area of the garden is called King Arthur's courtyard. It has long been a place of healing. The pool on the right is a shallow one now, but in the nineteenth century, it was much deeper, allowing for total immersion. It is now a place of quiet comtemplation with the sound of the falling water creating a soothing background

The Anti-Cancer Agent Collection

TAXOL

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Cancer Chemotherapy

The most difficult aspect of designing an anti-cancer agent is how to selectively kill the cancerous cells while leaving healthy cells intact. Because both types of tissue have almost identical metabolic enzymes, it becomes necessary to selectively target those enzymes that are more abundant and/or active in cancer cells.

FLUOROURACIL

Unfortunately, most of the chemicals that have been found to be efficacious anti-cancer agents are extremely toxic and must be administered very carefully. Still, the side effects displayed by these drugs are numerous and often, rather drastic.

ADRIAMYCIN

The photomicrograph displayed as the banner for this page depicts crystallites of one of the most promising anti-cancer agents yet developed, taxol, which is derived from the rare Pacific yew tree. This slow-growing tree has become the focus of a bitter argument between medical researchers and conservationists who argue that the existence of the yew is threatened by large harvests.

METHOTREXATE

Taxol acts to inhibit mitosis in tumor cells by binding to microtubule components. Recently, a major breakthrough was accomplished when Dr. Robert A. Holton announced a new synthetic pathway to this important drug using a more readily available material extracted from the needles of the more abundant English yew.

TAXOL

Our collection of pharmaceuticals contains a variety of anti-cancer agents. We are continually revising the collection as new drugs become available to us for photomicrography. Please return to this site often for updates on photomicrographs of anti-cancer agents.

Taxol" is used in these pages to refer to the drug that now has the generic name "paclitaxel", and the registered tradename "Taxol ®" (Bristol-Myers Squibb Company, New York. N.Y.)

A version utilising the Chime plug-in featuring embedded rotating molecular structures, is also available here, and a version using the ChemSymphony Java applets is available here.

Taxol

In the early 1960s, the National Cancer Institute (NCI) in the United States initiated a programme of biological screening of extracts taken from a wide variety of natural sources. One of these ex tracts was found to exhibit marked antitumour activity against a broad range of rodent tumours. Although this discovery was made in 1962, it was not until five years later that two researchers, Wall and Wani, of the Research Triangle Institute, North Carolina, isolated the active compound, from the bark of the Pacific yew tree (Taxus brevifolia). In 1971, Wall a nd Wani published the structure of this promising new anti-cancer lead compound, a complex poly-oxygenated diterpene (shown below).

Taxol - the 3D structure in pdb format can be viewed (using a suitable helper application such as Rasmol) by clicking on the image.

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Biological Profile

Despite its well documented biological activity, very little interest was shown in taxol until scientists at the Albert Einstein Medical College reported that its mode of action was totally unique. Until this finding in 1980, it was believed that the cytotoxic properties of taxol were due to its ability to destabilise microtubules, which are important structures involved in cell division (mitosis). In fact, taxol was found to induce the assembly of tubulin into microtubules, and more importantly, that the drug actually stabilises them to the extent that mitosis is disrupted. Such a novel mode of action was be lieved to make taxol a prototype for a new class of anticancer drugs.

Renewed interest in taxol led to major problems, since many groups wished to conduct clinical trials, and so large quantities of this material were required. The natural source, the Pacific yew tree (left), is an environmentally protected species, which is also one of the slowest growing trees in the world. Isolation of the compound, which is contained in the bark, involves killing the tree, and the quantities availabl e by this method are pitifully small. It would take six 100-year old trees to provide enough taxol to treat just one patient.

Luckily, a closely related analogue of taxol, called baccatin III was discovered in the leaves of a European species of ornamental shrub Taxus baccata. Although the extraction and subsequent chemical elaboration of bacc atin III to taxol was very laborious, the source was renewable, and sufficient quantities were obtained to carry out clinical trials. Results, published in 1989 showed that taxol exhibits very promis ing activity against advanced ovarian cancer, and in 1992, the US Food and Drug Administration (FDA) approved taxol for the treatment of this condition. The treatment of other types of cancer a lso looks promising, and in 1994, taxol was approved for breast cancer.

The relatively non-toxic properties of taxol have made it a leading light in the treatment of cancer in the 1990s, providing a non-intrusive alternative to the more radical techniques of radiotherapy and surgery. The cost of producing sufficient quantities of this new wonderdrug, however, is a severely limiting factor. Synthetic organic chemistry may provide a solution to this problem in the years to c ome.

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Total Synthesis of Taxol

Taxol represents an enormous challenge to the ingenuity and creativity of the synthetic organic chemist.

Three total syntheses have been carried out to date. The Holton group and Nicolaou group published their approaches in 1994, and very recently, Danishefsky and co-workers reported their route to taxol. Many other groups worldwide are continuing to carry out research in this area, in order to develop newer and shorter routes to this natural product, but also with a view to creating modified structures which may be more biol ogically active. Such groups include the Magnus researchers at Austin, Texas, and the Wender group at Stanford who have published their results recently, amongst others.

The Holton Route

Holton used (-)-borneol as his starting material, which he converted to an unsaturated ketone over 13 chemical steps. This ketone was converted into ß-patchouline oxide

which was epoxidised and treated with a Lewis acid, which induced a skeletal rearrangement, providing tertiary alcohol. This alcohol was again epoxidised, and underwent a fragmentation reaction to create the A and B rings of taxol. The C- ring was introdu ced using the Robinson-Stork annulation methodology.

These reactions outline the general route that Holton employed to synthesise taxol. The full synthesis can be found in J.Am.Chem.Soc. (1994) 116, 1597 and 1599.

The Nicolaou Route

The route utilised by Nicolaou was a convergent (rather than a linear) route, the A- and C-rings being constructed separately, and then linked together using a Shapiro reaction to connect the southern part, and a McMurray coupling reaction to complete the B-ring.

Having created the fused A, B and C ring system, Nicolaou then went on to complete the total synthesis of taxol. For more detailed information see Nature (1994) 367, 630; J.Chem.Soc. Chem.C ommun. (1994) 295 and J.Am.Chem.Soc. (1994) 116, 1591.

The Danishefsky Route

The method employed by Danishefsky started with the Wieland-Miescher ketone, which was elaborated to a complex enol triflate, bearing an olefin on the C-ring for development to taxol via an intramole cular Heck reaction.

Further details about Danishefsky's route to taxol can be found in J.Am.Chem.Soc. (1996) 118, 2843.

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TY'R YWEN? (Accommodation, Wales, UK).

"Ty'r Ywen" is Welsh for "House of the Yew trees" Like many farmhouses in the locality yew trees have been planted nearby. Yew is a slow growing extremely long lived tree whose foliage is deadly poisonous to most farm animals. Why then are these trees planted on a farm of all places?

The answer lies in history. Sometime in the twelvth century in the South Wales area a deadly weapon was devised. This weapon was to completely alter the balance of European power and wreak havoc on the battle field.

The weapon was the longbow, it's potential was realised by the kings of England and with it a devastating campaign was launched against the French in pursuit of dynastic claims on the European mainland.

This war lasted for a hundred years, the power of the longbow enabled greatly outnumbered English armies supported by contingents of South Wales archers to defeat the French in three major battles.

The longbow was six feet in length, the arrows were over three feet long. Longbows have been found that would have required a force of over 200lbs to draw them. Such a weapon had a maximum range of almost five hundred yards and an effective range of three hundred yards. At two hundred yards they were devastating. The arrows could penetrate four inches of oak, plate armour or chain mail. A competent archer could discharge an arrow every six seconds. His first three arrows would be in the air whilst he launched his fourth.

No man living today could have drawn such a bow, but then medieval archers trained from early childhood. The bow required no great technology in its manufacture, most of the materials were to hand. It could be made from ash or from elm but favourite was yew. As thousands of these bows were required many yew trees were planted.

A yew tree requires at least a hundred years growth to be big enough to provide suitable timber for a long bow. It is remarkable that people were prepared to plant trees for a war they would never see, or were they confident that there would always be wars?

In keeping with the long tradition we have recently planted five more yew trees to secure the future supply of long bows!

Yew Tree (Taxus baccata)

Grows to a hieght of fifty feet or so. Evergreen. Bisexual, ie. there are separate male and female trees. Nowadays it is used for topiary and hedging. Recently its foliage has been found to have anti-carcinogenic properties. The attractive, red coloured close grained timber is used for high class furniture and for veneers.

Abstract from Inventory Report

Area of pilot inventory on
North Vancouver Island

Two separate classification methods were tested in a stratified, random sampling design study to inventory Pacific Yew: ecosystem-based classification and forest-cover-based classification. The purpose was to identify strata with high concentrations of yew, for maximum precision and efficiency of the inventory. Results of a pilot study indicated that both approaches will identify such concentrations. While the ecosystem classification yields more precise estimates, the forest cover classification is more widely available. Strengths and weaknesses of both approaches, and differences in the estimates are discussed.

Yew Inventory Report

Yew is found as a very small and scattered component in some coastal and interior wetbelt regions in B.C. This scattered distribution is the most important factor in designing an inventory; it makes it critical to identify areas where concentrations of yew are significant. It has been stated from previous inventories that yew was not always found where it was expected and in B.C. it is sporadically distributed on a wide variety of sites in seral and climax forests.

The inventory study area for this project centered around Quatsino Sound on the northwest coast of Vancouver Island (Tree Farm License 6) in the coastal western hemlock and mountain hemlock biogeoclimatic zones. The area comprised over 170 000 hectares with eight ecosystem associations and nine forest cover/site class types. One hundred field plots (10 x 800) were established for each inventory (ecosystem based vs forest inventory based).

Although the precision of ecosystem based classification for identifying yew concentrations was higher, mapping at this level is much less common than the forest cover type. Estimated yew concentrations were 1.5 yew trees/ha with a standard error estimate of 0.23 for the ecosystem based classification and 2.1 yew trees/ha with a standard error estimate of 0.46 for the forest cover system. The study also noted yew was found in ecosystems other than old growth and that Pacific yew was regenerating well on cutovers.

Are Pacific yew trees available ?

Yes, a number of nurseries in British Columbia specialize in native plants including Pacific Yew. For lists of resources, please consult local authorities or search the web for sources in your area.

Can I grow Pacific yew in my area?

In British Columbia, first check the distribution map for Pacific yew and then check with local nurseries or contact the nearest B.C. Forest Service office.

How fast do yew trees grow?

Pacific yew grows slowly in the understorey of natural stands but under intensive nursery culture, can grow quite quickly.

How old do Pacific yew get?

Pacific yew generally live 200-300 years with some specimens 400 years or more.

How big do they get?

Pacific yew do not generally attain great heights but trees 25 meters tall have been recorded. Diameters are variable, but trees up to 0.85 meters (diameter at breast height) have been found.

Can Pacific yew survive in clear cuts?

Yes, foliage grown in shade however, may take on a bronzed appearance until it adjusts to full sun.

Can I propagate yew myself ?

Yes, cuttings can be rooted using conventional methods. To learn how, see the section on propagation.

Is bark currently being harvested in Canada for taxol production?

Yes, but only from sites being harvested for commercial timber supply. For current policy on Pacific yew harvest and or export from British Columbia, contact the B.C. Forest Service at http://www.for.gov.bc.ca/

If I am removing yew on my property does anyone want it?

There is no mechanism in place to utilize single yew trees.

What is the current status of taxol?

Medical use of taxol is increasing every day. There are a multitude of web sites with the most recent medical research.

Are taxol and paclitaxel the same?

Yes, Taxol is the trade name for Bristol-Myers Squibb's preparation while paclitaxcel is the chemical name. The name taxol is by far the most commonly used.

How does taxol work?

During cell division, taxol interferes with the development of the microtubules needed for cell duplication thus inhibiting the faster growing tumor cells. This is different than other anti-cancer agents that work by interfering with the DNA of tumor cells.

Do you do any research on taxol?

No, we are not engaged in research aimed at taxol production; rather we study conservation and cultivation options for Pacific yew.

Can I use Pacific yew as a herbal remedy?

The use of yew in any form for any medical or health reason should only done after consulting a health care professional.

Has taxol been chemically synthesized?

Yes, taxol has been synthesized and efforts to commercialize it are underway. It is also being produced using a semi-synthetic method utilizing foliage of English yew to provide the initial material which is then chemically converted to taxol.

How much taxol does a Pacific yew produce?

Although taxol content can vary it is found only in small quantities (0.001 to 0.01 % of the dry bark weight). It is generally considered to take 3 to 10 trees per patient. Based on data from the U.S. Forest Service from 1992, 36000 trees are required to provide 327200 kg of bark (about 9 kg/tree) from which 24 kg of taxol can be extracted. (about 0.66 g/tree). Approximately 1 kg is required for 480 cancer patients or 2.08 g per person or 3.15 trees per person. Others have claimed this number can be as high as 10 trees per person depending on the size of the trees.

Is Pacific yew bark the only natural source of taxol?

No, taxol is found in all yew species and in all parts of the tree (foliage, bark, roots) in varying concentrations.

Are there efforts underway to find high taxol-yielding Pacific yew trees?

Some surveys have been made but more commonly, fast growing hybrids are being used.

Where else can I look for information on Pacific yew?

More information is available through the British Columbia Ministry of Forests and United States Forest Service

Ordering information:
For information on how to order copies of reports or journal reprints, please visit the Pacific Forestry Centre's publications website.

Refereed Journals

Hogg, K.E., A.K. Mitchell and M. Clayton. 1996. Confirmation of cosexuality in Pacific yew (Taxus brevifolia Nutt.). The Great Basin Naturalist 56(4):377-378.

Marshall, Valin G., Marilyn R. Clayton and Deanna N. Newsom. 1998. Morphology, ontogony and intraspecific variability of the yew big bud mite, Cecidophyopsis psilaspis (Nalepa) (Acari: Eriophyidae). Can. Ent. 130: 285-304

Marshall, Valin G.& Marilyn R. Clayton. Biology and phenology of the yew big bud mite, Cecidophyopsis psilaspis (Nalepa) (Acari: Eriophyidae), in British Columbia. In preparation.

Mitchell, A.K. 1997 Propagation and growth of Pacific yew(Taxus brevifolia Nutt.) cuttings. Northwest Science, Vol.7(1):56-63

Mitchell, A.K., R.W. Duncan, T.A. Bown and V.G. Marshall. 1997 Origin and distribution of the yew big bud mite (Cecidophyopsis psilaspis) in British Columbia. Can. Ent.129:745-755

Mitchell, A.K. 1998. Acclimation of Pacific yew (Taxus brevifolia) foliage to sun and shade. Tree Physiology 18: 749-757

Mitchell, A.K. Ecophysiology of Pacific yew (Taxus brevifolia Nutt.) in preparation.

Reports

de Jong , R.J. and G. M. Bonner. 1995. Pilot Inventory for Pacific Yew. Forestry Canada and B.C. Ministry of. Forests, Victoria B.C. FRDA Rep. No. 231

Duncan, R. W., T.A. Bown, V.G. Marshall and A.K. Mitchell. 1997 Yew Big Bud Mite. Forest Pest Leaflet No.79 Canadian Forest Service Victoria B.C.

Lewis, T. 1993. Pacific Yew Inventory Design Evaluation of Proposed Methodology. For. Can., Pac. Yuk. Reg. 6p.

Mitchell, A.K. 1992 The yews and taxol: a bibliography (1970-1991). Forestry Canada, Pacific Forestry Centre, Inf. Rept. BCX-338

Workshops and Conferences

Mitchell, A.K. 1992. Foliar physiology and morphology of Taxus brevifolia and Taxus baccata in winter. In: Proc. 12th North Am. For. Biol. Workshop. Edited and compiled by S.J. Columbo, G. Hogan and V. Wearn. Aug. 17-20, 1992, Sault Ste Marie, Ontario. P.81

Mitchell, A.K. 1992. Rooting cuttings of Pacific yew from Vancouver Island locations. Presented at the Forest Nursery Association of British Columbia, Annual Meeting. Oct. 3-5, 1992. Penticton

Mitchell, A.K, and T.A. Bown 1993. Values of Department of National Defence (DND) land on southern Vancouver Island: Pacific Yew In: Department of National Defence Lands Southeast Vancouver Island: Initial Evaluation of Knowledge and Notes from a Workshop Feb. 23, 1993. Prepared by: M. Lashmar. Canadian Wildlife Service, Delta B.C., 1994. pp.71-73.

Mitchell, A.K. 1994 Acclimation to stress in Pacific yew. North American Forest Biology Workshop, June 14-16, 1994. Baton Rouge, Louisiana. P 52.

Mitchell, A.K. 1995 Sustainable development of natural sources of taxol: Ecophysiology of Pacific yew (Taxus brevifolia) In Department of National Defence - CFB Esquimalt environmental science advisory committee 1995 annual report . Prepared by A. Robinson and J A Trofymow April 1996 Canadian Forest Service Victoria B.C. pp 49-52 pp. 88-91

Mitchell, A.K. 1996 Sustainable development of natural sources of taxol: Ecophysiology of Pacific yew (Taxus brevifolia) In: Department of National Defence - CFB Esquimalt environmental science advisory committee 1996 annual report . Prepared by A. Robinson and J A Trofymow March 1997 Canadian Forest Service Victoria B.C. pp 49-52

To restore Pacific yew to sites where it has been harvested, an efficient means of propagation is required, however at the start of this project little was known about vegetative propagation of Pacific yew. Therefore protocols based on rooting cuttings of other conifers, including other Taxus species, were utilized.

Propagation from seed was not considered a viable option. With few exceptions, seed production in Pacific yew is sparse and little is known about the viability of the seed. This is in sharp contrast to many of the horticultural varieties of yew which have been selected and propagated for their showy ornamental seed. Germination of Pacific yew seed is often difficult requiring long periods (up to two years) of stratification. Propagation by layering was observed in the field but proved unsuccessful in an initial trial in the lab and so that method of propagation was not pursued.

Transplanting of young yew trees from field sites was accomplished with moderate success. We collected about 100 trees from such areas and found that with smaller trees (under about 60cm) we had about a 50% success rate when transplanted into pots. This method was very time consuming and required great care to minimize root damage during removal. Propagation from cuttings was selected as the preferred method.

Propagation Methods

Sources of yew for cuttings

Setting cuttings in flats in the greenhouse

Branches growing in both sun and shade were collected from the mid to lower crown of mature male and female as well as juvenile Pacific yew from various locations on Vancouver Island. All material for cuttings was placed in plastic bags with some wet paper towel and stored at 2^o C. for no more than 10 days. Most cuttings for this study were made during the winter months. Some attempts were made to root cuttings taken in March and April with considerably lower success rates. This was probably the result of desiccation of the cuttings during the warm spring and summer months. Rootings would typically take four to five months to establish. Cuttings rooted with cool air and warm soil will probably give the best result.

It was observed that cuttings from young seedlings had a better success rate than those from mature trees and should be preferred if sex ratios are not a concern (juvenile trees rarely have seed or pollen cones from which to determine the sex). Overall rooting success was 70.8% for the juvenile cuttings compared to 48.6% for mature. Sex of the tree had little effect with overall rooting success with rates of 53.0% in the males and 47.2% in the females.

Cuttings from trees growing in sunny and shady conditions were compared. Cuttings from sunny locations showed a slightly better rooting at 50.7% compared to 41.5% from the shaded locations. Cuttings from a range of geographic locations on Vancouver Island showed no significant difference in rooting however clonal differences from individual trees did. Response from individual trees varied from 14.5% to 87.5%. It was encouraging that we succeeded in rooting some cuttings from every tree sampled regardless of age (>250 years), location or growing conditions.

Preparation of cuttings

Flat containing yew cuttings

Using a sharp razor blade, cuttings were taken from the healthiest looking branch ends with good apical shoot tips. Needles were then stripped from the bottom few centimeters. Cuttings were set in shallow wooden flats containing a mixture of equal parts of sand, peat and perlite.

Cuttings of two different lengths were made, 3-5 cm and 25-40cm. Rooting success was very similar at 55.7% and 50.6% respectively. The use of the larger cuttings would gain at least one year of growth but, if source material is limited, the more numerous smaller cuttings may be preferred.

The use of rooting hormone was tested. In our trial Stimroot 3 (Plant Products, Bramalea Ontario) containing 0.8% IBA (indolebutyric acid) was used. The base of the cuttings were dipped in the rooting hormone powder. This increased rooting success from 30.6% to 50.0%.

Wounding the base of the cutting was found to be beneficial. Using a sharp blade, a small slice of bark up to 2 cm long and 2 mm wide was removed from the largest cuttings prior to being dipped in the rooting powder (this can be done with a simple downward slice with the blade). This tended to increase the number of roots and produce a more fibrous root system. Layering of some stem segments was tried with no success.

Rooting can take four to five months or, in some cases, longer. Great care must be taken when checking for rooting as the new roots are very brittle and easily broken.

Propagation Box

Dr. Alan Mitchell with propagation box

An outside cutting box [see diagram] was used based on a design developed and used at Pacific Forestry Centre. A layer of 5-6cm. of sand was placed in the bottom of the box in which heating cables maintained a bottom heat of 20 ⁰C. (heating cables can be obtained from most horticultural suppliers). Mist chambers in the greenhouse were also utilized but algae and slime molds were a problem given the long rooting time. Once in the rooting box, care must be taken to maintain high humidity. This however can lead to problems with gray mold. Allowing space between the cuttings for ventilation can help or, if need be, a registered fungicide can be used. It was found yew cuttings did well with light levels as low as 15% of full sun. Another concern is the yew big bud mite. Close examination of the buds on the cuttings should be made and the appropriate miticide used either as a dip at the time of setting or later as a spray.

Rooted Cuttings

Rooted cuttings were potted in 3:1 peat and sand in 4-inch pots and placed in a lath house with about 50% shade. Cuttings were watered as required and fertilized monthly with 20-20-20 at 100ppm. Bronzing of the foliage will likely occur if the trees are left in full sun.

First roots

In our trials, the rooted cuttings were held for two years. Growth averaged 3.4 cm. in the first year and 15.7 cm. in the second year. Growth in the second year appeared to have a strong clonal influence with some clones producing exceptional growth up to 60cm in a single season. Based on our observations, with the right conditions many yew trees are capable of excellent growth rates in sharp contrast to their tendency to grow slowly in natural stands. A drawback to using branches for cutting material is that most of the resulting cuttings show a plagiotropic or branch like form.

This can be avoided by making cuttings from upright shoots but where this is not possible staking of the young trees may be required.

Potted Pacific yew are very susceptible to root weevils. The cuttings should be checked occasionally for damage just below the soil level. If a problem exists, check into what the best local control options are. We have used both insecticides and physical barriers to restrict weevil access to the pots. Some biological controls are also now available.

Outplanting

Unfortunately information on the outplanting of propagated Pacific yew is very limited. At this time, we have no plans for any large-scale closely monitored trials. We have, however, planted 100 seedlings (fall 1997) on a wooded slope on the grounds of the Pacific Forestry Centre. An initial check indicates we have had at least a 95% survival during the first winter. We intend to follow the progress of these trees for several years. A further 800 trees were included for planting on federal lands by prison inmates in the spring of 1998. We expect some observations on the success of these trees within a year or so.

A brief description in the process of crafting a self bow:
Each bow begins with a piece of wood referred to as a stave. In photo #1, you can see examples of Osage and Yew staves and a roughed out bow in the center. With Osage and many other woods it important to follow a growth ring the entire length of the bow because one growth ring will be the back of the bow and will be under a great deal of stress. Photo #2 is an example of the yearly growth rings which are revealed by the end cut of an Osage stave. Photo #1 Osage Orange and Yew stave with a roughed out Osage bow in the center. Photo #2 End cut of an Osage stave showing yearly growth rings.		Once the back of the stave has been prepared, it is then time to reduce the width and thickness of the stave in rough form as shown in the first photo. Next comes the process of removing wood from the belly until the stave will bend. This process continues until the entire stave bends in a smooth arc and ultimately becomes a bow. At this point, the tillering process begins. I have written an article describing the method I use in the tillering process. You will be able to read this article in the October issue of Primitive Archer magazine.

Paclitaxel [33069-62-4]

Synonyms: Taxol; Taxal; Taxol A; 7,11-Methano-5H-cyclodeca[3,4]benz[1,2-b]oxete,benzenepropanoic acid deriv.; TAX; 5-beta,20-epoxy-1,2-alpha,4,7-beta,10-beta,13-alpha-hexahydroxy-tax-11-en-9-one 4,10-diacetate 2-benzoate 13-ester with (2R,3S)-N-benzoyl-3-phenyl-isoserine;

C₄₇H₅₁NO₁₄

853.9182

ACX : X1009807-6

Melting poin 213 – 216°C

RTECS: WX1272100

Comments: Antineoplastic. Needles (in aqueous methanol)

Taxol - Molecule of the Month

....web page by Hitesh J. Sanganee and Karl Harrison

Introduction

Taxol (1), a potent anticancer natural product (with activity against a number of leukeamias and solid tumours in the breast, ovary, brain, and lung^l in humans) has stimulated an intense research effort over recent years. Taxol was isolated from the bark of the pacific yew ( Taxus brevifolia Nutt ) in 1971 and the structure elucidated by Wani and Wall². The initial biological activity was related to the microtubule-destabilizing properties of the vinca alkaloids.³ However, research by Horwitz et al ⁴ indicated that the biological activity was in fact unique. It was shown to have a complementary effect: i.e. binding to polymerised tublin, stabilising it against disassembly and consequently inhibiting mitosis.

Phase I clinical trails began in 1983 with Taxol in short supply. Research efforts intensified on the synthesis and a number of groups began their approaches. It concluded after a decade in the total synthesis by Holton ^5,6 and Nicolaou⁷ simultaneously. However the total synthesis was preceded by the more efficient semisynthesis of Taxol from baccatin III (2)^7,8,9 which enabled compounds to be administered in clinical tests. As a result, the semisynthesis approaches have recently been utilised in the synthesis of analogues in order to (i) understand the molecular basis of its activity, (ii) synthesise a more potent Taxol analogue with higher selectivity for tumour cells, (iii) synthesise a molecule with limited complexity but similar mechanism of action of Taxol.

Structure Activity Relationships

The structure activity relationships of taxol has been studied by a multitude of researchers. The molecule can divided into two parts; the side chain and taxol skeleton .

Side Chain
The side chain of taxol is critical for maintaining activity. The structure activity of the side has been studied by Potier ¹⁰ and Swindell¹¹. The studies have revealed the following features:

• Protection of the C2' hydroxyl group as a ester results in loss of activity in terms of microtublin stabilization but not in cytotoxicity.
• The C3' amide-acyl group is critical but may be aromatic or alkyl in nature.
• The C3' bound nitrogen can be replaced by a oxygen atom without loss of activity.
• The C3' aryl group is needed, replacement by a methyl group reduces the activity 19-fold.

Taxol Skeleton
Taxol consists of several rings: a four membered ring and a six membered ring and eight membered ring and peripheral functionalities. Modification of the taxol skeleton and elucidation of its structure activity have lead to the following features:

• The oxetane ring is crucial for maintaining the activity, ring opening leads to a dramatic decrease in bioactivity.
• Contraction of the eight membered ring to a seven membered ring still provides the molecule with tublin depolymerization properties.
• Removal of the C10 acetyl group does not have any effect on the activity.
• C2-O-benzoyl group removal causes a drastic reduction to activity.

YEW (Taxus baccata) Type: Plain Local/Other Names: Yewtree Origin: Europe Available Thickness: Comment:

An Overview

Taxol was initially extracted from the bark of the Pacific yew Taxus brevifolia in the 1960's. Since that time its use as an anti-cancer drug has become well established. Taxol is now also being used in a wide variety non-cancer related medical applications. The Pacific yew and taxol is a compelling example of the unknown values in forests.

Although the ethnobotanical records have shown that some of the medicinal properties of yew have been known for centuries it wasn't until 1966 that Pacific yew was included in a massive screening of 35,000 species by the United States National Cancer Institute. Monroe Wall, a chemist from North Carolina, discovered taxol extracted from the bark of Pacific yew as the one outstanding compound having anticancer activity.

By 1971 Wall had described the molecular structure of taxol and said that it had the most promising suppression of tumor cells he had ever seen. Without the support of the National Cancer Institute, Wall gave up without patenting taxol.

In 1977 Wall's findings were confirmed and by 1979 taxol's unique mode of action [see Questions and answers for more information]was worked out by a team of New York pharmacologists and its publication was noticed by the National Cancer Institute.

Human trials started in 1983 and continued until 1989. Despite a few deaths caused by unforeseen allergic reactions due to the form in which the drug was administered great promise was shown for women with previously incurable ovarian cancer. This led the National Cancer Institute to issue a contract with Bristol Myers-Squibb, a pharmaceutical company based in the United States, for the clinical development of taxol

Since 1989, taxol has been the subject of intense research. New findings are being announced on an almost weekly basis. Taxol research is being carried out on ovarian cancer, breast cancer, colon and gastric cancers, lung cancer, arthritis, Alzheimer's, as an aid in coronary and heart procedures and as an antiviral agent. Yew concentrate has also recently been marketed as a herbal medicine. The use of yew in any form for any medical or health reason should only done after consulting a health care professional.

Intense research on finding alternatives to taxol extracted from the bark of the Pacific yew is ongoing. Taxol has been chemically synthesized and semi-synthetic versions have been developed using needles and twigs from other yew species grown in agricultural settings. This is reducing the pressure on natural stands of Pacific yew but bark is still being used for taxol production.

TRIGLAVSKI NARODNI PARK

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Na podlagi 335.člena in 33.alinee prvega odstavka 342.člena ustave Socialistične republike Slovenije, 27.alinee prvega razdelka 71.člena in trejtega odstavka 243.člena poslovnika Skupščine SR Slovenije je Skupščina Socialistične republike Slovenije na sejah Zbora zrduženega dela in Zbora občin dne 26.maja 1976 sprejela

ODLOK o zavarovanju redkih in ogroženih rastlinskih vrst

1.člen
Za zavarovane redke ali ogrožene rastlinske vrste (v nadaljnjem besedilu: zavarovane rastlinske vrste) se v smislu 9.člena zakona o varstvu narave (Uradni list SRS, št. 7-21/70) razglašajo:

1.Bela žrdana (Amanita ovoidea)
2.Lepi čeveljc (Cypripedium calceolus)
3.Blagayev volčin (Daphne blagyana)
4.Dišeči volčin (Daphne cneorum)
5.Sternbergov klinček (Dianthus sternbergii)
6.Alpska možina (Eryngium alpinum)
7.Močvirska logarica ali močvirski tulipan (Fritillaria meleagris)
8.Gorska logarica (Fritillaria tenella)
9.Clusijev svišč (Gentiana clusii)
10.Froelihov svišč (Gentiana froelichi)
11.Košutnik ali rumeni svišč (Gentiana lutea)
12.Kochov svišč (Gentiana kochiana)
13.Panonski svišč (Gentiana pannonica)
14.Bodika (Ilex aquifolium)
15.Planika (Leontopodium alpinum)
16.Brstična lilija (Lilium bulbiferum)
17.Kranjska lilija (Lilium carniolium)
18.Žafranasta lilija (Lilium croceum)
19.Ozkolistna narcisa (Narcissus stellaris)
20.Rdeča murka (Nigritella miniata)
21.Črna murka (Nigritella nigra)
22.Avrikelj ali lepi jeglič (Prumula auricula)
23.Kranjski jeglič (Primula carniolica)
24.Velikonočnica (Pulsatilla grandis)
25.Rjasti sleč (Rhododendron ferrugineum)
26.Rumeni sleč (Rhododendron luteum)
27.Širokolistna lobodika (Ruscus hypoglossum)
28.Tisa (Taxus baccata)

2.člen
Rastline zavarovanih vrst je prepovedano uničevati (trgati, ruvati, izkopavati, obsekavati, sekati), prenašati z naravnih rastišč, prodajati ter izvažati ali odnašati v tujino.
Ne glede na določbe prvega odstavka lahko Republiški sekretariat za urbanizem dovoli izkopavanje, prenašanje in gojitev rastlin zavarovanih rastlinskih vrst ter njihovo razpošiljanje, odnašanje ali izvoz v tujino, če je to potrebno za znanstveno-raziskovalno delo, za vzgojo (botanični vrtovi in podobno) ali za razmnoževanje zavarovanih rastlinskih vrst.


3.člen
Naravna rastišča zavarovanih rastlinskih vrst smejo proučevati in raziskovati domače znanstveno raziskovalne organizacije ali posamezniki, ki imajo za to dovoljenje Republiškega sekretariata za urbanizem.
Tuje znanstveno-raziskovalne organizacije in tujci lahko raziskujejo rastišča zavarovanih rastlinskih vrst, če pridobijo dovoljenje po določbah odloka o vrstah znanstveno-raziskovalnega dela, za katere je tujcem potrebno dovoljenje (Uradni list SFRJ, št.27-332/70) in dovoljenje po določbah prvega odstavka tega člena.


4.člen
Lastnik oziroma imetnik pravice uporabe zemljišča je dolžan omogočiti proučevanje in raziskovanje zavarovanih rastlinskih vrst in njihovih rastišč ter izkopavanje zavarovanih rastlinskih vrst tistim, ki imajo za to dovoljenje po 2. oziroma 3. členu tega odloka.


5.člen
Izvršni svet Skupščine SR Slovenije predpiše z uredbo ukrepe za varstvo in način izkoriščanja gospodarsko pomembnih samoniklih okrasnih in zdravilnih rastlinskih vrst.


6.člen
Ko začne veljati ta odlok, prenehajo v skladu z določbami 22.člena zakona o varstvu narave veljati:
1.odredba o zavarovanju redke flore (Uradni list LRS, št.23-138/47);
2.odredbi o dopolnitvi odredbe o zavarovnju redke flore (Uradni list LRS, št.26-155/47 in št.20-121/49).


7.člen
Ta odlok začne veljati osmi dan po objavi v Uradnem listu SRS


Št.63-26/76
Ljubljana, dne 26.maja 1976

Skupščina Socialistične republike Slovenije
Predsednik
Marijan Brecelj l.r

WESTERN YEW
taxus brevifolia

• also known as Pacific Yew
• some historians believe that the bow Robin Hood used was made from English yew; hence 'taxus', the Latin word for "bow"

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UNIQUE FEATURES:

• taxol, which is used in some cancer treatment, is derived from the bark of the western yew
• food for elk, deer, moose, caribou
• food for elk, deer, moose, caribou
• square shape in young trees becoming more coneshaped with age
• branches spread horizontally, or sweeping downwards, trunk is twisted

LOCATION:

• wetter forests in the coast and interior of BC
• low to mid elevations
• areas of abundant soil nutrients

SIZE:

• 5 to 15 metres in height
• appears like a low spreading shrub or small tree

CONES/FRUIT:

• pollen cones are produced on the male trees
• seed cones, produced on the female tree, appear as a coral-red/salmon coloured, fleshy "berry" which contains a single seed

NEEDLES:

• shiny, flat, sharp, pointed tip
• the top side is a darker green than any other conifer, the underside is a pale yellowish-green
• ridge down the centre
• arranged spirally on twigs

BARK:

• thin, scaly
• dark reddish or purplish
• rose coloured underbark is exposed when scales peel off

WOOD CHARACTERISTICS:

• dense, strong, resilient

USES:

• modern - taxol
• traditional - bows, tools, paddles, snowshoe frames; the fruit, although considered toxic, was sometimes eaten in small amounts; inner bark: braiding, weaving

Cecidophyopsis psilaspis (Nalepa)
Adult female

In science you often find things you didn't know you were looking for. Inspection of yew branch samples destined for cutting material frequently turned up growth deformities in the shoots. Closer observation showed almost every bud collected from Pacific yew in coastal locations was infested with the yew big bud mite. This was in sharp contrast to samples collected in the interior of the province which were found to be mite free. Since that finding,the staff at the Pacific Forestry Centre have since established the distribution of this pest in British Columbia, reviewed the evidence that it may have been introduced, documented the damage to Pacific yew, and gained considerable insight to the mite's biology.

Very old English yew in Victoria's Ross Bay Cemetery

Between 1994 and 1995 branch samples were collected from 81 locations throughout the range of Pacific yew in British Columbia. All of the samples from the interior (38 in total) were mite free. The coastal samples, however, were all infested with the exception of the 3 samples collected from high elevation sites (>700m). In some cases the branches showed no symptoms, but close inspection revealed low numbers of mites. This may indicate some level of tolerance to the mite.

This same mite has long been a pest of yew in Europe. As it seems unlikely this species would have remained identical to it's European counterpart for tens of thousands -- if not millions -- of years, introduction seems likely. Since English yew was a horticultural favorite of 19th century British immigrants, the mite could easily have been introduced at that time.

Further distribution through wind dispersion, birds or insects may have spread the mite throughout the coast. Lack of dispersion to the interior may be a result of geographic barriers and an inability to tolerate the lower temperatures. This may also explain why high elevation areas on the coast (>700m) were mite free. Great care should be taken not to transport infested yew to mite-free areas.

Damage

Damage to the buds can range from slight swelling and marginal scorch of the bud scales to grotesque hypertrophy and complete necrosis of the bud. Repeated loss of terminal buds and subsequent shoot growth from lateral buds results in an erratic and asymmetrical growth form. As well new growth often has twisted and distorted needles.

Normal Yew

Abnormal Yew

Damaged Bud

Distorted Foliage

Side shoot on a twig

Big Bud mite larvae hatching

Adult Big Bud mite and eggs

Biology

The yew big bud mite appears to have a direct form of life cycle with egg, larva, nymph and adult stages being present in overlapping generations throughout the year. No special overwintering form (deutogyne) has been observed.

Description

Egg
Opaque white, about 30 µm. in diameter, spherical when first laid becoming somewhat oblong as the larva develops.

Larva
Approximately 88 - 103 µm. in length,translucent white, similar to the nymph but smaller.

Nymph
Approximately 117 - 143 µm. in length, opaque white; similar to adults except in size and colour.

Adult
Approximately 126 - 159 µm. in length, orange brown, vermiform or worm-like in body shape, with two pairs of legs (rather than four as in most mites) located at the anterior end. Although similar in appearance, males are smaller in size (126 -139 µm.) than females (139 - 159 µm.).

Pacific yew (Taxus brevifolia)

(click on each photo to enlarge image)

• Needles: About 1" long; dark green above and lighter green below (not white); pointed, but not sharp; leaf margins rolled under; needles occur in a single plane.
• Fruit: Small red "berry" with a single large seed (actually an aril). POISONOUS!
• Bark: Thin, purple, and scaly.
• Distribution: Native to the Pacific coastal region from southeastern Alaska southward into California. Occur from 2,100-8,000 ft. (650-2,500 m) elevation.

For more information about this species, see p. 56 of "Trees to Know in Oregon".