Taxus baccata is an Old World species of evergreen tree in the family Taxaceae. It is the tree originally known as yew, though to distinguish it from related species it is sometimes called common yew, European yew, or, in North America, English yew. It is a woodland tree in its native range, including much of Eurasia and Northwest Africa. All parts of the plant except the fleshy aril are poisonous, with toxins that can be absorbed through inhalation, ingestion, and transpiration through the skin. The wood has been prized for making longbows and for musical instruments such as lutes. Yews are often grown as ornamental trees, hedges or topiaries, including in churchyards, where they sometimes reach great age; many explanations have been given for this planting, especially that the yew is associated with death, immortality, and rebirth. Some place names derive from the Proto-Celtic *eburos, but scholars disagree as to whether this meant the yew tree.
Taxonomy The species Taxus baccata was first described in 1753 by Carl Linnaeus in his Species Plantarum. The name remains accepted, despite the many descriptions by later taxonomists, resulting in 108 synonyms. Linnaeus created the generic name Taxus, perhaps from the Greek toxon, a bow. The word yew is from Old English īw, ēow, ultimately from Proto-Indo-European *h₁eyHw-, via Proto-Germanic *iwo, which also gave rise to Celtic forms such as Old Irish ēo, Welsh ywen. It became Old English iw, eow and Middle English eu. Baccata is Latin for 'bearing berries'.
Description Yews are small to medium-sized evergreen trees, growing up to 10–20 metres (35–65 ft) or exceptionally 28 m (92 ft) tall, with a trunk up to 2 m (6+1⁄2 ft) or exceptionally 4 m (13 ft) in diameter. The bark is thin, scaly reddish-brown, and comes off in small flakes aligned with the stem. The leaves are flat, dark green, 1–4 centimetres (1⁄2–1+1⁄2 in) long, 2–3 millimetres (1⁄16–1⁄8 in) broad, and arranged spirally on the stem, but with the leaf bases twisted to align the leaves in two flat rows on either side of the stem, except on erect leading shoots where the spiral arrangement is more obvious. The seed cones are modified, each cone containing a single seed, which is 4–7 mm (3⁄16–1⁄4 in) long and almost surrounded by a fleshy scale which develops into a soft, bright red berry-like aril. The aril is 8–15 mm (5⁄16–9⁄16 in) long and wide and open at the end. The arils mature 6 to 9 months after pollination. The aril is gelatinous and very sweet tasting. The male cones are globose, 3–6 mm (1⁄8–1⁄4 in) in diameter, and shed their pollen in early spring. Yews are mostly dioecious with male and female cones on separate trees, but occasional individuals can be variably monoecious, or change sex with time.
Distribution The yew is native to all countries of Europe (except Iceland), the Caucasus, and beyond from Turkey eastwards to northern Iran. Its range extends south to Morocco and Algeria in North Africa, and parts of Southwest and South Asia. A few populations are present in the archipelagos of the Azores and Madeira. The limit of its northern Scandinavian distribution is its sensitivity to frost, with global warming predicted to allow its spread inland. It has been introduced elsewhere, including the United States.
Habitat and ecology The yew's richest central European populations are in Swiss yew-beech woodlands, on cool, steep marl slopes up to 1,400 metres (4,600 ft) in elevation in the Jura Mountains and Alpine foothills. In the UK it grows best on steep slopes of the chalk downs, forming extensive stands invading the grassland outside the beech woods. In more continental climates of Europe it fares better in mixed forests of both coniferous and mixed broadleaf-conifer composition. Under its evergreen shade, no other plants can grow. The species prefers steep rocky calcareous slopes. It rarely develops beyond saplings on acid soil when under a forest canopy, but is tolerant of soil pH when planted by humans, such as their traditional placement in churchyards and cemeteries, where some of the largest and oldest trees in northwestern Europe are found. It grows well in well-drained soils, tolerating nearly any soil type, typically humus and base-rich soils, but also on rendzina and sand soils given adequate moisture. They can survive temporary flooding and moderate droughts. Roots can penetrate extremely compressed soils, such as on rocky terrain and vertical cliff faces. It normally appears individually or in small groups within the understory, but forms stands throughout its range, such as in sheltered calcareous sites. It is extremely shade-tolerant, with the widest temperature range for photosynthesis among European trees, able to photosynthesize in winter after deciduous trees have shed their leaves. It can grow under partial canopies of beech and other deciduous broad-leafed trees, though it only grows into large trees without such shade. The arils are eaten by birds, which disperse the hard seeds undamaged in their droppings. Although they contain toxins, the kernels are extracted and eaten by some birds, such as hawfinches, greenfinches, and great tits.
Conservation Historically, yew populations were gravely threatened by felling for longbows and destruction to protect livestock from poisoning. It is now endangered in parts of its range due to intensive land use. The species is also harvested to meet pharmaceutical demand for taxanes. Trees are often damaged by browsing and bark stripping. Yew's thin bark makes it vulnerable to fire. Its toxicity protects against many insects, but the yew mite causes significant bud mortality, and seedlings can be killed by fungi. Clippings from ancient specimens in the United Kingdom, including the Fortingall Yew, were taken to the Royal Botanic Gardens in Edinburgh to form a mile-long hedge. The purpose of this "Yew Conservation Hedge Project" is to maintain the DNA of Taxus baccata. A conservation programme was run in Catalonia in the early 2010s by the Forest Sciences Centre of Catalonia in order to protect genetically endemic yew populations and preserve them from overgrazing and forest fires. In the framework of this programme, the 4th International Yew Conference was organised in the Poblet Monastery in 2014. There has been a conservation programme in northern Portugal and Northern Spain (Cantabrian Range).
Harmfulness
Toxicity
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