Dodonaeus over Taxus
Het heet in Nederduitse iben-boom, yevenhout, in het Engels yewtree, in het Frans if of yf, in het Hoogduits Ibenbaum of Eybenbaum, Boheemse tis’.
In oud-Nederlands was het ijf, yfboom, iebenboom of ieve, Eda, Ebichholtz in midden-Hoogduits, Eibe bij Cordus, Eibenbaum, Id, Aida, Eie, Ey, I, Iba, Ibe, Iben, Ibenbaum bij Bock en later bij Hildegard, Inf, Iboum, Ibsche, If, Ie, Ifenbaum, Ige, ook Iwa in oud-Hoogduits en Iigo, Ilvenholt, Iwenbaum bij Hildegard, Jeda, Yb, Ybe en Pippenholz, oud-Noors yr, Angelsaksisch en Keltisch iw en toen ifig, ife, eow, ewe en nu yew, oud-Hoogduits Iwa, Ifenbaum, Eibel en nu Eibe, in Zwitserland Eya, Jali en Ibe, eibe: eeuwig, naar het altijdgroene loof. In noordelijke streken heet het ook Eda en Jeda, dat gif betekent, (ook voor Hedera) ook Id en Aida dat gloed betekent vanwege het gebruik van het hout om de gloed van het vuur te behouden of naar de rode kleur van het hout, Duits Gluth, Rossbaum en Roteib’n.
De eibennamen hebben de Germanen alleen met de Kelten gemeen. Het Gallische ivos, dat in Frans if en Spaans en Portugees iva voortleeft, het Ierse eo, Kymrisch yw(en) en het Bretonse ivin voeren terug op het oer Keltisch iu-os. Oerverwant is de Griekse naam voor de lijsterbes dat gevormd is uit oiua en Latijn uva: tros, in het Armeens is aigi de naam voor de wijnstok. Daarna betekenen Indogermaanse oiua, eiua en iua namen van gewassen die door hun bessen opvielen.
Natuur
De ibenboom is heel venijnig en de menselijke naturen heel tegengesteld.
Kracht en werking.
De ibenboom wordt niet tot profijt van de mensen gebruikt, het is zo schadelijk en venijnig dat diegene die er onder de schaduw van slapen ziek worden en soms ook sterven, vooral als het bloeit en in Gascogne waar deze boom het aller schadelijkste is.
Als de mensen de vruchten eten krijgen ze tenminste de loop van de buik en de vogels sterven daar van of veranderen hun veren.
De ongeleerde apothekers gebruiken de schorsen van deze boom voor de schorsen van Tamariscus en daaraan kan je zien wat voor groot kwaad die ongeleerde apothekers dagelijks doen als ze slechte en schadelijke dingen voor goede medicijn geven tot groot nadeel van de arme, zieke mensen.
Daarom zou het wel nodig zijn dat de dokters hun medicijnen zelf maakten net als Hippocrates, Galenus en alle ouders gedaan hebben of dat er tenminste regel gesteld werd op het feit en werk van de apothekers zoals wij hiervoor ook vermeld hebben.
Giftigheid Taxus
Alle delen van de taxus - met uitzondering van het rode vruchtvlees van de rode schijnbessen - bevatten een heel krachtig gif, het taxine, dat ook na het drogen, koken of bewaren actief blijft. Daarnaast bevat taxus prikkelende vluchtige oliën. De naalden hebben het hoogste taxinegehalte.
Taxine is een cardiotoxische stof die eerst een prikkelende, daarna een verlammende werking op het hart en het ademhalingscentrum van mens en dier heeft. Taxine zelf is niet irriterend: de irritatie die bij een taxusvergiftiging optreedt in het maag-darmstelsel wordt veroorzaakt door de vluchtige oliën. Bij de mens treden één tot twee uur na het eten van zaden of naalden de volgende verschijnselen op: braken, diarree, buikkrampen, duizeligheid, hallucinaties, verwijding van de pupillen. Bij een zware intoxicatie volgen daarna stuipen, een onregelmatige polsslag, hartritmestoornissen, een sterke daling van de bloeddruk en een plotse dood door hart- en ademhalingsstilstand.
Ook dieren, en in het bijzonder paarden zijn bijzonder gevoelig voor de giftige taxus.
Het vruchtvlees zonder pit is goed eetbaar. Zacht zoet van smaak en slijmerig.
Mythologie van de Taxus
In de christelijke cultuur is de taxus symbool voor dood en rouw. Men vindt hem daarom ook vaak op kerkhoven. Tevens is hij - vanwege zijn altijd groene naalden - zinnebeeld voor onsterfelijkheid en eeuwigheid. Bij de Kelten was de taxus symbool voor de Winterzonnewende (21 december).
In zijn boek ‘The Celtic Druids’ zegt Godfrey Higgins dat het best mogelijk is dat het Engelse woord yew voor taxus in verband zou kunnen staan met het woord Jehova. Als dat zo is dan betekent Yew Boom van God.
Het woord taxus is afgeleid van het Griekse taxon wat boog betekent, want van taxushout werden bogen en schilden gemaakt. Van taxus is het woord toxisch (giftig) afgeleid. Het verwijst naar de giftige delen van de boom. Anderen beweren dat taxus komt van het Latijnse texo wat weven betekent. De taxusbast werd vroeger namelijk ook gebruikt voor weef - en vlechtwerk.
De Engelse sjamaan Dusty Miller vervaardigt wandelstokken en andere voorwerpen van taxushout. Voordat hij van een boom een tak snijdt, vraagt hij eerst om toestemming en vervolgens om zijn levenskracht niet uit deze tak terug te trekken. Daarom noemt hij zijn voorwerpen Leefhout.
Bomen hebben, net als mensen, een ziel of een 'Hoger Zelf', de dryade Dit woord werd al door de oude Grieken gebruikt. De Dusty's zeggen dat dit woord door de dryaden geaccepteerd is. De Dusty's werken sinds generaties samen met dryaden in een zeer oud bos in Zuidoost-Engeland. .Het hout dat zij van hen ontvangen, blijft levend, omdat het een kloon van van de oorspronkelijke dryade herbergt. Dit is alleen maar mogelijk door hun vriendschaps - en vertrouwensband met de Dusty's. De dryaden kunnen een identiek duplicaat van zichzelf produceren en dit in de geschonken tak achterlaten. Zij geven ook een precieze aanwijzing waar en hoe de tak afgezaagd moet worden. De Dusty's nemen dit Leefhout mee en bewaren het meerdere jaren, terwijl de dryade in dit hout een verdere ontwikkeling doormaakt. Zij geeft aan, wanneer dit hout bewerkt mag worden. dryade
De dryaden die aan de Dusty's Leefhout schenken, zijn zeer oud en ervaren. Bezield hout was al vroeger bekend. Toverstaven b.v. zouden van leefhout gemaakt zijn.
Dryaden en mensen hebben veel gemeen. Beide zijn de hoogst ontwikkelde wezens in het plantenrijk respectievelijk het rijk der zoogdieren.Beide streven ernaar hun kennis te verruimen en aan hun persoonlijke ontwikkeling te werken. Voor beide geldt ook, dat zij een individu zijn. Er zijn mensen die zich helemaal niet voor bomen interesseren. Er zijn dryaden die zich absoluut niet voor mensen interesseren. De dryaden die met de Dusty's samen werken , zijn zowel aan mensen als ook aan hun eigen ontwikkeling geïnteresseerd.
Een oude taxus (taxus baccata) heeft volgens de Dusty's een bijzonder hoog ontwikkelde dryade.
Taxus brevifolia (pacific yew)
English Common Names
Pacific yew, western yew, American yew, Oregon yew, bowplant, mountain mahogany.
French Common Names
If de l'ouest, if occidental.
Morphology
Pacific yew is an evergreen, spindly tree, usually growing to a height of 6 - 10 m, and a diameter of 15-30 cm. One yew in western Washington had a record diameter of 1.4 m, and some trees are reported to have grown as high as 25 m. In drier, eastern parts of its range Pacific yew is found in open areas as a shrub less than 2 m high. Male trees produce small but abundant yellowish flowers on the underside of the branches. Female trees produce seeds enclosed in pulpy, sweet, red or scarlet arils (fleshy, berry-like structures), not cones as do most other Coniferae. The single seed of the fruit often protrudes beyond its outer cover. The foliage is relatively sparse. The trunk is tapered and usually fluted, and covered by scaly, reddish-brown to purplish-brown bark only 2-6 mm thick. Thin, purple scales of the outer bark are easily removed, exposing a reddish-purple under-bark. Lower branches contacting the soil will root, and cut stumps will sprout, producing clumps of trees. Yew trees are slow-growing and long-lived.
Classification and Geography
Six to 20 species of Taxus are recognized, depending on authority, with two species indigenous to Canada. The shrubby Canada yew (T. canadensis Marsh., also known as American yew and ground hemlock) occurs from Manitoba eastwards, and southwards into the US. This poisonous plant was used medicinally by North American Indians. Pacific yew is native to the mountains of western North America. It ranges from southeast Alaska to northern California, and from the Pacific coast to interior Idaho and Montana. Occasional trees are found as far south as San Francisco.
Ecology
Pacific yew normally grows inconspicuously and slowly beneath a conifer forest canopy, in dense shade. The species is not abundant, generally occurring in small groups or single trees. It grows best on cool, moist flats along streams, in deep gorges and damp ravines, and where fires are relatively infrequent. The seeds are disseminated by birds. Deer, elk, and moose sometimes browse on the foliage, although Taxus species are considered unpalatable to livestock, and poisoning has been reported for some of the species.
Medicinal Uses
Indigenous Peoples of North America used the bark, foliage, and fruits of yew medicinally. Bella Coola Indians used leaf tea for lung ailments; Chehalis Indians employed leaf preparations to induce healthful sweating; Cowlitz used poultices of ground leaves on wounds; and Karok drank twig bark tea to relieve stomach ache.
An anti-cancer compound taxol (paclitaxel) is present in yew trees. Taxol is active against advanced refractory ovarian cancer (for which treatment alternatives are limited), as well as breast cancer, and it is undergoing clinical trials for efficacy against a variety of other cancers. Taxol is therapeutic because it is a mitotic spindle poison which inhibits uncontrolled cancerous growths (i.e. the spindle apparatus which aligns chromosomes during cell division (mitosis) is disrupted, preventing cancer cells from reproducing). Cancer is the second most frequent cause of death in industrialized countries, and improved treatments are urgently needed. It has been estimated that in the future over a quarter million people could be treated yearly with taxol, and that the drug could have a commercial value of the order of $1 billion annually. Taxol treatment is presently expensive, the drug costing between $10 000.00 and $100 000.00 for each patient, depending on number of treatment cycles (one to ten).
Toxicity
Although yew trees are now viewed as a tree of life, ironically they were once known as the tree of death. This is because all parts of all species of Taxus, except the fleshy arils, can be quite poisonous to humans and livestock. Most references state that the "fleshy fruits" (i.e., the cup-like arils) are edible, but the seed within each aril can be deadly, and could be ingested unintentionally. Therefore, eating the arils is not recommended. The English yew is the most toxic native plant in Britain. Because yew species are so poisonous, no one should attempt self-medication.
Chemistry
The anti-cancer compound taxol (paclitaxel) is contained in most parts of yew trees, but is especially concentrated in the inner bark (i.e., the cambium). The word Taxol (with a capital T) is a registered trademark name for a drug formulated with paclitaxel (cf. "Coke" and "coke").
Non-medicinal Uses
Traditionally, Native North Americans valued the extremely hard, decay-resistant wood for tools like canoe paddles and fish hooks, weapons like archery bows and spears, and ceremonial and decorative items. Gunstocks, boat decking, veneer, snowshoe frames, furniture, musical instruments, and sculptures have all been made of yew in recent times. Archery bows and canoe paddles continue to be manufactured from yew. The wood is still used occasionally by craftsmen, and for firewood and fence wood, and the plant is sometimes grown as an ornamental. The hybrid yew (Taxus × media Rehd. = T. baccata × T. cuspidata) is the most frequently cultivated species in southern Ontario, the largest region of ornamental yew cultivation in Canada (J.B. Phipps, personal communication). In Canada and the northern US, Japanese yew (Taxus cuspidata Sieb. & Zucc.) is frequently cultivated, and all parts of this except the fleshy red fruits are very toxic.
Agricultural and Commercial Aspects
Until recently, Pacific yew has been considered a nuisance weed by modern forestry, insufficiently important to harvest for lumber or pulp. It was often burned along with logging slash that remained after timber harvest. In 1962, the National Cancer Institute of the US found that extracts from Pacific yew bark showed in vitro activity against cancer cells. Thus began a period of stardom for this hitherto largely ignored "trash species," which was turned into "Cinderella of the Great Western Woods." Coincidentally, this period of celebrity overlaps that of another rare species of older western forests, the spotted owl. The seriously declining owl population unfortunately led to the polarization of environmentalists and loggers as to whether habitat or jobs is more important. An even more painful ethical dilemma was raised by the yew tree: whether saving trees or victims of cancer is more important. Of course, this is an artificial debate: the maximum yield from natural stands can only be obtained by limiting harvests to sustainable levels, and following habitat-conservation principles.
Yew bark is usually harvested by cutting the tree down, peeling the bark off the trunk and larger limbs using chisels or hatchets, and bagging the bark. Studies of damaged trees have suggested that killing entire trees, in many cases over 100 years old, is unnecessarily wasteful, and that removal of bark from one side allows the tree to survive without seriously affecting growth, and thus provides more bark for future harvests. The bark is chipped, dried, and its taxol extracted. Illegal harvest by poachers on public and private lands has become a major problem in the US and Canada. Unfortunately the yield of taxol from the bark is extremely small: < 0.02% dry weight. A single women suffering from ovarian cancer might need as much as 3 g of taxol, which would require the bark of 7.5 average yew trees. One study indicated an average requirement of six 100-year-old trees per cancer patient. About 7270 kg of bark is required to produce 1 kg of taxol. About 726 000 kg of Pacific yew bark were harvested in 1991. Projected demands over the next 20 years could require sacrificing as many as a million trees a year, a figure which is well beyond the available supply of wild trees. Coupled with the facts that the Pacific yew is rare and very slow growing, the expanding demand has made it clear that wild trees cannot provide adequate supplies. Decimation of trees led to the US government in 1992 passing The Yew Act to ensure sustainable management of the yew harvest.
Several alternatives to harvesting wild Pacific yew to obtain taxol are now being developed. These include: establishing yew plantations, not just of Pacific yew, but of several cultivated species (all other species of Taxus of the world produce taxol, although in lower concentrations); breeding high-taxol cultivars of Taxus; production using tissue culture; production from Taxomyces, a newly-named genus of fungus isolated from Taxus, which also produces taxol (an apparent example of natural exchange of the genes responsible for taxol synthesis between higher plants and fungi); full synthesis; and synthesis of chemical analogues. These alternatives are currently being explored by numerous laboratories and intensive cultivation in forest tree nurseries has begun. However, at present the chief means of augmenting the supply of taxol obtained from bark is a partial synthesis of taxol starting with extracted chemicals from the foliage of species of Taxus (often collected abroad). This is a welcome development since the foliage can be harvested regularly without sacrificing the plants.
The story of Pacific yew is instructive. It demonstrates how research on biodiversity can uncover invaluable materials and information. It illustrates the need to preserve biodiversity options for future generations. It reminds us of how unchecked human greed can quickly threaten a natural resource. It also shows how wise stewardship of an ecosystem can be achieved to ensure sustainable harvest of a natural resource of great importance to people.
Myths, Legends, Tales, Folklore, and Interesting Facts
Some Pacific yew trees may live for over 500 years, and it has been suggested that one tree reached the age of 1800 years. It has been claimed that an English yew is the world's second oldest living tree. One English yew tree is believed to be over 4000 years old. [Claims of world's longest living tree have been made for a pair of closely related species in the southern US Rockies, Pinus aristata Engelm. (bristlecone pine) and for another pine with which it is often combined, P. longaeva Bail. (ancient pine); one tree named "Methuselah" was found to be 4 723 years old and is said to be the world's oldest known living tree. Ironically after studying the world's oldest organism, the discoverer, Edmund Schulman, died of a heart attack at the comparatively young age of 49.]
Vancouver Island Indians used yew to make paddles for their dugout canoes. Because the paddles were heavy and sharp, they could double as weapons.
In the Willamette Valley, Oregon, Native Americans were often buried with their yew bows.
The English yew has the distinctions of being known as the tree from which famous archers such as Robin Hood and William Tell made their bows. Arthur Conan Doyle (1859-1930), creator of Sherlock Holmes, wrote:
What of the bow?
The bow was made in England;
Of true wood, of yew wood,
The wood of English bows;
So men who are free
Love the old yew tree,
And the land where the yew tree grows.
In England, yews have a particular association with graveyards. This is because Druids appear to have planted yews at sacred sites, which were taken over by Christians, who built their churches there, establishing nearby graveyards. It has been suggested that the yews are able to live for many centuries because they are nourished by the calcium-rich soil left by the bones of the dead. According to one myth, the roots of yew trees in graveyards enter the mouths of the deceased, grow down their throats, envelope their hearts, and whisper their secrets in the breeze. Alfred Lord Tennyson (1809-1892), Poet Laureate of England, wrote (in his poem In Memoriam):
Old Yew, which graspest at the stones
That name the underlying dead,
Thy fibers net the dreamless head,
Thy roots are wrapt about the bones.
The International Union for the Conservation of Nature recently issued a report showing that 33 798 of the 270 000 known species of plants (about one in eight) are in danger of extinction. The report stated that 15 of 20 species of yew trees are threatened.
Some garden books have recommended burning yew clippings to ward off insects - a dangerous practice since poisonous constituents may be carried in the smoke.
In 1991 a leathery corpse that has become known as "The Ice Man," deep-frozen for about 5300 years, was found trapped in a glacier on the Austrian/Italian Alps. Beside his body was found a little axe handle and a bow, both made of yew wood.
Selected References
Adams, J.D., Flora, K.P., Goldspiel, B.R., Wilson, J.W., Arbuck, S.G., and Finley, R. 1993. Taxol: a history of pharmaceutical development and current pharmaceutical concerns. J. Natl. Cancer Inst. Monogr. 15: 141-147.
Anon. 1992. Taxol news. Bioeng. News 13(11): 5-6.
Anon. 1992. Medicinals from India. Herbalgram 27: 7, 58-59.
Anon. 1993. Taxol from fungus. Biotech. News 13(12): 7-8.
Bailey, J.D., and Liegel, L.H. 1997. Response of Pacific yew (Taxus brevifolia) to partial removal of the overstory. West. J. Appl. For. 12(2): 41-43.
Borman, S. 1991. Scientists mobilize to increase supply of anticancer drug taxol. Chem. Eng. News 69(35): 11-18.
Busing, R.T., Halpern, C.B., and Spies, T.A. 1995. Ecology of Pacific yew (Taxus brevifolia) in western Oregon and Washington. Conserv. Biol. 9: 1199-1207.
Choi, M.S., Kwak, S.S., Liu, J.R., Park, Y.G., Lee, M.K., and An, N.H. 1995. Taxol and related compounds in Korean native yews (Taxus cuspidata). Planta Med. 61: 264-266.
Crawford, R.C., and Johnson, F.D. 1985. Pacific yew (Taxus brevifolia) dominance in tall forests, a classification dilemma. Can. J. Bot. 63: 592-602.
DeFuria, M.D., and Horovitz, Z. 1992. Taxol commercial supply strategy. In Proceedings of the second National Institute Workshop on Taxol and Taxus, Alexandria, VA. pp. 195-198.
Difazio, S.P., Vance, N.C., and Wilson, M.V. 1996. Variation in sex expression of Taxus brevifolia in western Oregon. Can. J. Bot. 74: 1943-1946.
Difazio, S.P., Vance, N.C., and Wilson, M.V. 1997. Strobilus production and growth of Pacific yew under a range of overstory conditions in western Oregon. Can. J. For. Res. 27: 986-993.
Donehower, R.C., and Rowinsky, E.K. 1993. An overview of experience with taxol (paclitaxel) in the U.S.A. Cancer Treat. Rev. 19(Suppl. C): 63-78
Edgington, S.M. 1991. Taxol out of the woods. Bio/Tech. 9: 933-934.
El-Kassaby, Y.A., and Yanchuk, A.D. 1994. Genetic diversity, differentiation, and inbreeding in Pacific yew from British Columbia. J. Hered. 85: 112-117.
Elsohly, H.N., Croom, E.M., el-Kashoury, E.S., elSohly, M.A., and McChesney, J.D. 1994. Taxol content of stored fresh and dried Taxus clippings. J. Nat. Prod. 57: 1025-1028.
Georg, G.I, Chen, T.T., Ojima, I., and Vyas, D.M. (Editors). 1995. Taxane anticancer agents: basic science and current status. ACS Symposium Series 583, American Chemical Society, Washington, DC. 353 pp.
Göçmen, B., Jermstad, K.D., Neale, D.B., and Kaya, Z. 1996. Development of random amplified polymorphic DNA markers for genetic mapping in Pacific yew (Taxus brevifolia). Can. J. For. Res. 26: 497-503.
Hamon, N.W. 1993. Yew. Can. Pharm. J. 126: 192, 196, 199-200.
Hartzell, H., Jr. 1991. The yew tree: a thousand whispers: the biography of a species. Hulogosi, Eugene, OR. 318 pp.
Heiken, D.O. 1992. The Pacific yew and taxol: federal management of an emerging resource. J. Environ. Law and Litigation 7: 175-245.
Hils, M.H. 1993. Taxaceae. In Flora of North America north of Mexico, Vol. 2. Edited by Flora of North America Editorial Committee. Oxford University Press, New York, NY. pp. 423-427.
Hogg, K.E., Mitchel, A.K., and Clayton, M.R. 1996. Confirmation of cosexuality in Pacific yew (Taxus brevifolia Nutt.). Great Basin Nat. 56: 377-378.
Joyce, L. 1991. Scientists take wide variety of approaches to taxol studies. The Scientist 5(24): 15, 20, 22.
Kingston, D.G.I. 1993. Taxol, an exciting anticancer drug from Taxus brevifolia. Am. Chem. Soc. Symp. Ser. 534: 138-148.
McAllister, D.E., and Haber, E. 1991. Western yew - precious medicine. Can. Biodiversity 2: 2-4.
Minore, D., and Weatherly, H.G. 1994. Effects of partial bark removal on the growth of Pacific yew. Can. J. For. Res. 24: 860-862.
Minore, D., and Weatherly, H.G. 1996. Stump sprouting of Pacific yew. U.S. For. Serv. Gen. Tech. Rep. PNW 378: 1-6.
Minore, D., Weatherly, H.G., and Cartmill, M. 1996. Seeds, seedlings, and growth of Pacific yew (Taxus brevifolia). Northwest Sci. 70: 223-229.
Mitchell, A.K. 1997. Propagation and growth of Pacific yew (Taxus brevifolia Nutt.) cuttings. Northwest Sci. 71(1): 56-63.
Murray, M.D. 1991. The tree that fights cancer. Am. For. 97(7-8): 52-54.
Nicholson, R. 1992. Death and Taxus: the yew is an unlikely candidate for the tree of life. Nat. Hist. 9: 20.
Nicolaou, K.C., R.K. Guy, and P. Potier. 1996. Taxoids: New weapons against cancer. Sci. Am. 274(6): 94-98.
Nicolaou, K.C.,Yang, Z., Liu, J.J., Ueno, H., Nantermet, P.G, Guy, R.K, et al. 1994. Total synthesis of taxol. Nature 367: 630-634.
Piesch, R.F., and Wheeler, N.C. 1993. Intensive cultivation of Taxus species for the production of taxol - Integrating research and production in a new crop plant. Acta Hortic. 344: 219-228.
Rae, C.A., and Binnington, B.D. 1995. Yew poisoning sheep. Can. Vet. J. 36: 446.
Rao, K.V. 1993. Taxol and related taxanes. I. Taxanes of Taxus brevifolia bark. Pharm. Res. 10: 521-524.
Rao, K.V., Bhakuni, R.S., Hanuman, J.B., Davies, R., and Johnson, J. 1996. Taxanes from the bark of Taxus brevifolia. Phytochemistry (Oxford) 41: 863-866.
Rao, K.V., Hanuman, J.B., Alvarez, C., Stoy, M., Juchum, J., Davies, R.M., and Baxley, R. 1995. A new large-scale process for taxol and related taxanes from Taxus brevifolia. Pharm. Res. 2: 1003-1010.
Scher, S., and Jimerson, T.M. 1989. Does fire regime determine the distribution of Pacific yew in forested watersheds. U.S. Dep. Agric. Pac. Southwest For. Range Exp. Stn. Gen. Tech. Rep. 109. 160 pp.
Stierle, A., Strobel, G., and Stierle, D. 1993. Taxol and taxane production by Taxomyces andreanae: an endophytic fungus. Science 260(5105): 214-216.
Stierle, A., Strobel, G., Stierle, D., Grothaus, P., and Bignami, G. 1995. The search for a taxol-producing microorganism among the endophytic fungi of the Pacific yew, Taxus brevifolia. J. Nat. Prod. 58: 1315-1324.
Strobel, G.A., Stierle, A., and Hess, W.M. 1993. Taxol formation in yew -- Taxus. Plant Sci. 92: 1-12.
Suffness, M. (Editor). 1995. Taxol science and applications. CRC Press. Boca Raton, FL. 426 pp.
Vance, N.C., Kelsey, R.G., and Sabin, T.E. 1994. Seasonal and tissue variation in taxane concentrations of Taxus brevifolia. Phytochemistry 36: 1241-1244.
Wall, M.E., and Wani, M.C. 1995. Camptothecin and taxol: discovery to clinic - thirteenth Bruce F. Cain Memorial Award Lecture. Cancer Res. 55: 753-760
Walter-Vertucci, C., Crane, J., and Vance. N.C. 1996. Physiological aspects of Taxus brevifolia seeds in relation to seed storage characteristics. Physiol. Plant. 98: 1-12.
Werth, J.Von Der, and Murphy, J.J. 1994. Cardiovascular toxicity associated with yew leaf ingestion. Br. Heart J. 72(1): 92-93.
Wheeler, N.C. 1993. Taxology: a study in technology commercialization. J. For. 91(10): 15-18.
Wheeler, N.C., Jech, K., Masters, S., Brobst, S.W., Alvarado, A.B., Hoover, A.J., and Snader, K.M. 1992. Effects of genetic, epigenetic, and environmental factors on taxol content in Taxus brevifolia and related species. J. Nat. Prod. 55: 432-440.
Wheeler, N.C., Jech, K.S., Masters, S.A., O'Brien, C.J., Timmons, D.W., Stonecypher, R.W., and Lupkes, A. 1995. Genetic variation and parameter estimates in Taxus brevifolia (Pacific yew). Can. J. For. Res. 25: 1913-1927.
Whiterup, K.M., Look, S.A., Stasko, M.W., Ghiorzi, T.J., Muschik, G.M., and Cragg, G.M. 1990. Taxus spp. needles contain amounts of taxol comparable to the bark of Taxus brevifolia: analysis and isolation. J. Nat. Prod. 53: 1249-1255.
World Wide Web Links
(Warning: The quality of information on the internet varies from excellent to erroneous and highly misleading. The links below were chosen because they were the most informative sites located at the time of our internet search. Since medicinal plants are the subject, information on medicinal usage is often given. Such information may be flawed, and in any event should not be substituted for professional medical guidance.)
Fire effects information system:
http://svinet2.fs.fed.us/database/feis/plants/shrub/taxbre/
Medical attributes of Taxus brevifolia -- the Pacific yew, by M. Costello and K. Kellmel:
http://wilkes1.wilkes.edu/~kklemow/Taxus.html
Pacific yew & taxol, by A. Mitchell:
http://www.pfc.cfs.nrcan.gc.ca/ecosystem/yew/
L'if de l'Ouest et le taxol, par A. Mitchell:
http://www.pfc.cfs.nrcan.gc.ca/ecosystem/yew/index_f.html
Taxol (Paclitaxel),The cancerBACUP factsheet:
http://www.cancerbacup.org.uk/info/factsheet/taxol.htm
Taxol: an exciting anticancer compound:
http://c267b.chor.ucl.ac.be/taxol.htm
Taxol, purpose & side effects:
http://www.bmi.net/mcaron/taxol.html
Taxol and the yew tree, by N.J. Lawrence:
http://uchii1.ch.umist.ac.uk/group/subtopics/treeoflife.html
The history of taxol:
http://www.missouri.edu/~chemrg/210w97/taxol_bodypage.htm
Taxol, by N. Edwards: