Taxus cuspidata

Taxus cuspidata, the Japanese yew or spreading yew, is a member of the genus Taxus, native to Japan, Korea, northeast China and the extreme southeast of Russia. It is an evergreen tree or large shrub growing to 10–18 m tall, with a trunk up to 60 cm diameter. The leaves are lanceolate, flat, dark green, 1–3 cm long and 2–3 mm broad, arranged spirally on the stem, but with the leaf bases twisted to align the leaves in two flattish rows either side of the stem except on erect leading shoots where the spiral arrangement is more obvious. The seed cones are highly modified, each cone containing a single seed 4–8 mm long partly surrounded by a modified scale which develops into a soft, bright red berry-like structure called an aril, 8–12 mm long and wide and open at the end. The arils are mature 6–9 months after pollination. Individual trees from Sikhote-Alin are known to have been 1,000 years old. It is widely grown in eastern Asia and eastern North America as an ornamental plant. The entire yew bush, except for the fleshy berry surrounding the seed, is toxic due to a group of chemicals called taxine alkaloids. Yew poisonings are relatively common in both domestic and wild animals who consume the plant accidentally. Taxine B, the most toxic of the taxine alkaloids, is a cardiotoxin which works by disrupting the calcium and sodium currents of the myocardial cells. The taxine alkaloids are absorbed quickly from the intestine and in high enough quantities can cause death due to cardiac arrest or respiratory failure. Ingesting yew causes symptoms such as dizziness, dilation of pupils, abdominal pain, nausea and an irregular heartbeat. The minimum lethal dose (LDmin) of yew leaves is 3.0-6.5 mg/kg body weight for humans, 1–2 mg/kg for horses and 82.5 mg/kg for chickens. There is currently no known antidotes for yew poisoning but drugs such as atropine have been used to treat the symptoms.