Taxus baccata is a species of evergreen tree in the family Taxaceae, native to western, central and southern Europe (including the British Isles), northwest Africa, northern Iran and southwest Asia. It is the tree originally known as yew, though with other related trees becoming known, it may now be known as common yew, English yew, or European yew. It is primarily grown as an ornamental. Most parts of the plant are poisonous, and consumption of the foliage can result in death.
It is a small to medium-sized evergreen tree, growing 10–20 m (35–65 ft) (exceptionally up to 28 m or 92 ft) tall, with a trunk up to 2 m (6 ft 7 in) (exceptionally 4 m or 13 ft 1 in) in diameter. The bark is thin, scaly brown, coming off in small flakes aligned with the stem. The leaves are flat, dark green, 1–4 centimetres (0.39–1.57 in) long and 2–3 millimetres (0.079–0.118 in) broad, arranged spirally on the stem, but with the leaf bases twisted to align the leaves in two flat rows either side of the stem, except on erect leading shoots where the spiral arrangement is more obvious. The leaves are poisonous.
The seed cones are modified, each cone containing a single seed, which is 4–7 mm (3⁄16–1⁄4 in) long, and partly surrounded by a fleshy scale which develops into a soft, bright red berry-like structure called an aril. The aril is 8–15 mm (5⁄16–9⁄16 in) long and wide and open at the end. The arils mature 6 to 9 months after pollination, and with the seed contained, are eaten by thrushes, waxwings and other birds, which disperse the hard seeds undamaged in their droppings. Maturation of the arils is spread over 2 to 3 months, increasing the chances of successful seed dispersal. The seeds themselves are poisonous and bitter, but are opened and eaten by some bird species including hawfinches, greenfinches and great tits.
The aril is not poisonous, it 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. The yew is mostly dioecious, but occasional individuals can be variably monoecious, or change sex with time.